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7.2. 二叉树遍历
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0. 写在前面
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1. 引言
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1.1. 算法无处不在
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1.2. 算法是什么
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1.3. 小结
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2. 复杂度分析
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2. 复杂度分析
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2.1. 算法效率评估
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2.2. 时间复杂度
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2.3. 空间复杂度
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2.4. 小结
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3. 数据结构与类型
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< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_4_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_4" >
< span class = "md-nav__icon md-icon" > < / span >
3. 数据结构与类型
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_data_structure/classification_of_data_structure/" class = "md-nav__link" >
3.1. 数据结构分类
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_data_structure/basic_data_types/" class = "md-nav__link" >
3.2. 基本数据类型
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_data_structure/number_encoding/" class = "md-nav__link" >
3.3. 数字编码 *
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_data_structure/character_encoding/" class = "md-nav__link" >
3.4. 字符编码 *
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_data_structure/summary/" class = "md-nav__link" >
3.5. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_5" >
< label class = "md-nav__link" for = "__nav_5" id = "__nav_5_label" tabindex = "0" >
4. 数组与链表
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_5_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_5" >
< span class = "md-nav__icon md-icon" > < / span >
4. 数组与链表
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_array_and_linkedlist/array/" class = "md-nav__link" >
4.1. 数组
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_array_and_linkedlist/linked_list/" class = "md-nav__link" >
4.2. 链表
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_array_and_linkedlist/list/" class = "md-nav__link" >
4.3. 列表
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_array_and_linkedlist/summary/" class = "md-nav__link" >
4.4. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_6" >
< label class = "md-nav__link" for = "__nav_6" id = "__nav_6_label" tabindex = "0" >
5. 栈与队列
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_6_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_6" >
< span class = "md-nav__icon md-icon" > < / span >
5. 栈与队列
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_stack_and_queue/stack/" class = "md-nav__link" >
5.1. 栈
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_stack_and_queue/queue/" class = "md-nav__link" >
5.2. 队列
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_stack_and_queue/deque/" class = "md-nav__link" >
5.3. 双向队列
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_stack_and_queue/summary/" class = "md-nav__link" >
5.4. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_7" >
< label class = "md-nav__link" for = "__nav_7" id = "__nav_7_label" tabindex = "0" >
6. 散列表
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_7_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_7" >
< span class = "md-nav__icon md-icon" > < / span >
6. 散列表
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_hashing/hash_map/" class = "md-nav__link" >
6.1. 哈希表
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_hashing/hash_collision/" class = "md-nav__link" >
6.2. 哈希冲突处理
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_hashing/summary/" class = "md-nav__link" >
6.3. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--active md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_8" checked >
< label class = "md-nav__link" for = "__nav_8" id = "__nav_8_label" tabindex = "0" >
7. 树
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_8_label" aria-expanded = "true" >
< label class = "md-nav__title" for = "__nav_8" >
< span class = "md-nav__icon md-icon" > < / span >
7. 树
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../binary_tree/" class = "md-nav__link" >
7.1. 二叉树
< / a >
< / li >
< li class = "md-nav__item md-nav__item--active" >
< input class = "md-nav__toggle md-toggle" type = "checkbox" id = "__toc" >
< label class = "md-nav__link md-nav__link--active" for = "__toc" >
7.2. 二叉树遍历
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< a href = "./" class = "md-nav__link md-nav__link--active" >
7.2. 二叉树遍历
< / a >
< nav class = "md-nav md-nav--secondary" aria-label = "目录" >
< label class = "md-nav__title" for = "__toc" >
< span class = "md-nav__icon md-icon" > < / span >
目录
< / label >
< ul class = "md-nav__list" data-md-component = "toc" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "#721" class = "md-nav__link" >
7.2.1. 层序遍历
< / a >
< nav class = "md-nav" aria-label = "7.2.1. 层序遍历" >
< ul class = "md-nav__list" >
< li class = "md-nav__item" >
< a href = "#_1" class = "md-nav__link" >
算法实现
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "#_2" class = "md-nav__link" >
复杂度分析
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item" >
< a href = "#722" class = "md-nav__link" >
7.2.2. 前序、中序、后序遍历
< / a >
< nav class = "md-nav" aria-label = "7.2.2. 前序、中序、后序遍历" >
< ul class = "md-nav__list" >
< li class = "md-nav__item" >
< a href = "#_3" class = "md-nav__link" >
算法实现
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "#_4" class = "md-nav__link" >
复杂度分析
< / a >
< / li >
< / ul >
< / nav >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item" >
< a href = "../array_representation_of_tree/" class = "md-nav__link" >
7.3. 二叉树数组表示
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../binary_search_tree/" class = "md-nav__link" >
7.4. 二叉搜索树
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../avl_tree/" class = "md-nav__link" >
7.5. AVL 树 *
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../summary/" class = "md-nav__link" >
7.6. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_9" >
< label class = "md-nav__link" for = "__nav_9" id = "__nav_9_label" tabindex = "0" >
8. 堆
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_9_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_9" >
< span class = "md-nav__icon md-icon" > < / span >
8. 堆
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_heap/heap/" class = "md-nav__link" >
8.1. 堆
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_heap/build_heap/" class = "md-nav__link" >
8.2. 建堆操作 *
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_heap/summary/" class = "md-nav__link" >
8.3. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_10" >
< label class = "md-nav__link" for = "__nav_10" id = "__nav_10_label" tabindex = "0" >
9. 图
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_10_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_10" >
< span class = "md-nav__icon md-icon" > < / span >
9. 图
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_graph/graph/" class = "md-nav__link" >
9.1. 图
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_graph/graph_operations/" class = "md-nav__link" >
9.2. 图基础操作
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_graph/graph_traversal/" class = "md-nav__link" >
9.3. 图的遍历
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_graph/summary/" class = "md-nav__link" >
9.4. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_11" >
< label class = "md-nav__link" for = "__nav_11" id = "__nav_11_label" tabindex = "0" >
10. 搜索算法
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_11_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_11" >
< span class = "md-nav__icon md-icon" > < / span >
10. 搜索算法
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_searching/binary_search/" class = "md-nav__link" >
10.1. 二分查找（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_searching/binary_search_edge/" class = "md-nav__link" >
10.2. 二分查找边界（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_searching/replace_linear_by_hashing/" class = "md-nav__link" >
10.3. 哈希优化策略
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_searching/searching_algorithm_revisited/" class = "md-nav__link" >
10.4. 重识搜索算法
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_searching/summary/" class = "md-nav__link" >
10.5. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_12" >
< label class = "md-nav__link" for = "__nav_12" id = "__nav_12_label" tabindex = "0" >
11. 排序算法
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_12_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_12" >
< span class = "md-nav__icon md-icon" > < / span >
11. 排序算法
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/sorting_algorithm/" class = "md-nav__link" >
11.1. 排序算法
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/selection_sort/" class = "md-nav__link" >
11.2. 选择排序（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/bubble_sort/" class = "md-nav__link" >
11.3. 冒泡排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/insertion_sort/" class = "md-nav__link" >
11.4. 插入排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/quick_sort/" class = "md-nav__link" >
11.5. 快速排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/merge_sort/" class = "md-nav__link" >
11.6. 归并排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/heap_sort/" class = "md-nav__link" >
11.7. 堆排序（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/bucket_sort/" class = "md-nav__link" >
11.8. 桶排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/counting_sort/" class = "md-nav__link" >
11.9. 计数排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/radix_sort/" class = "md-nav__link" >
11.10. 基数排序
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_sorting/summary/" class = "md-nav__link" >
11.11. 小结
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_13" >
< label class = "md-nav__link" for = "__nav_13" id = "__nav_13_label" tabindex = "0" >
12. 回溯算法
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_13_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_13" >
< span class = "md-nav__icon md-icon" > < / span >
12. 回溯算法
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_backtracking/backtracking_algorithm/" class = "md-nav__link" >
12.1. 回溯算法（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_backtracking/permutations_problem/" class = "md-nav__link" >
12.2. 全排列问题（ ）
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_backtracking/n_queens_problem/" class = "md-nav__link" >
12.3. N 皇后问题（ ）
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_14" >
< label class = "md-nav__link" for = "__nav_14" id = "__nav_14_label" tabindex = "0" >
13. 附录
< span class = "md-nav__icon md-icon" > < / span >
< / label >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_14_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_14" >
< span class = "md-nav__icon md-icon" > < / span >
13. 附录
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "../../chapter_appendix/installation/" class = "md-nav__link" >
13.1. 编程环境安装
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "../../chapter_appendix/contribution/" class = "md-nav__link" >
13.2. 一起参与创作
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item md-nav__item--section md-nav__item--nested" >
< input class = "md-nav__toggle md-toggle " type = "checkbox" id = "__nav_15" >
< div class = "md-nav__link md-nav__link--index " >
< a href = "../../chapter_reference/" > 参考文献< / a >
< / div >
< nav class = "md-nav" data-md-level = "1" aria-labelledby = "__nav_15_label" aria-expanded = "false" >
< label class = "md-nav__title" for = "__nav_15" >
< span class = "md-nav__icon md-icon" > < / span >
参考文献
< / label >
< ul class = "md-nav__list" data-md-scrollfix >
< / ul >
< / nav >
< / li >
< / ul >
< / nav >
< / div >
< / div >
< / div >
< div class = "md-sidebar md-sidebar--secondary" data-md-component = "sidebar" data-md-type = "toc" >
< div class = "md-sidebar__scrollwrap" >
< div class = "md-sidebar__inner" >
< nav class = "md-nav md-nav--secondary" aria-label = "目录" >
< label class = "md-nav__title" for = "__toc" >
< span class = "md-nav__icon md-icon" > < / span >
目录
< / label >
< ul class = "md-nav__list" data-md-component = "toc" data-md-scrollfix >
< li class = "md-nav__item" >
< a href = "#721" class = "md-nav__link" >
7.2.1. 层序遍历
< / a >
< nav class = "md-nav" aria-label = "7.2.1. 层序遍历" >
< ul class = "md-nav__list" >
< li class = "md-nav__item" >
< a href = "#_1" class = "md-nav__link" >
算法实现
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "#_2" class = "md-nav__link" >
复杂度分析
< / a >
< / li >
< / ul >
< / nav >
< / li >
< li class = "md-nav__item" >
< a href = "#722" class = "md-nav__link" >
7.2.2. 前序、中序、后序遍历
< / a >
< nav class = "md-nav" aria-label = "7.2.2. 前序、中序、后序遍历" >
< ul class = "md-nav__list" >
< li class = "md-nav__item" >
< a href = "#_3" class = "md-nav__link" >
算法实现
< / a >
< / li >
< li class = "md-nav__item" >
< a href = "#_4" class = "md-nav__link" >
复杂度分析
< / a >
< / li >
< / ul >
< / nav >
< / li >
< / ul >
< / nav >
< / div >
< / div >
< / div >
< div class = "md-content" data-md-component = "content" >
< article class = "md-content__inner md-typeset" >
< a href = "https://github.com/krahets/hello-algo/tree/main/docs/chapter_tree/binary_tree_traversal.md" title = "编辑此页" class = "md-content__button md-icon" >
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< / a >
< h1 id = "72" > 7.2. 二叉树遍历< a class = "headerlink" href = "#72" title = "Permanent link" > ¶ < / a > < / h1 >
< p > 从物理结构的角度来看，树是一种基于链表的数据结构，因此其遍历方式是通过指针逐个访问节点。然而，树是一种非线性数据结构，这使得遍历树比遍历链表更加复杂，需要借助搜索算法来实现。< / p >
< p > 二叉树常见的遍历方式包括层序遍历、前序遍历、中序遍历和后序遍历等。< / p >
< h2 id = "721" > 7.2.1. 层序遍历< a class = "headerlink" href = "#721" title = "Permanent link" > ¶ < / a > < / h2 >
< p > 「层序遍历 Level-Order Traversal」从顶部到底部逐层遍历二叉树， < / p >
< p > 层序遍历本质上属于「广度优先搜索 Breadth-First Traversal」， < / p >
< p > < img alt = "二叉树的层序遍历" src = "../binary_tree_traversal.assets/binary_tree_bfs.png" / > < / p >
< p align = "center" > Fig. 二叉树的层序遍历 < / p >
< h3 id = "_1" > 算法实现< a class = "headerlink" href = "#_1" title = "Permanent link" > ¶ < / a > < / h3 >
< p > 广度优先遍历通常借助「队列」来实现。队列遵循“先进先出”的规则，而广度优先遍历则遵循“逐层推进”的规则，两者背后的思想是一致的。< / p >
< div class = "tabbed-set tabbed-alternate" data-tabs = "1:10" > < input checked = "checked" id = "__tabbed_1_1" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_2" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_3" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_4" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_5" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_6" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_7" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_8" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_9" name = "__tabbed_1" type = "radio" / > < input id = "__tabbed_1_10" name = "__tabbed_1" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_1_1" > Java< / label > < label for = "__tabbed_1_2" > C++< / label > < label for = "__tabbed_1_3" > Python< / label > < label for = "__tabbed_1_4" > Go< / label > < label for = "__tabbed_1_5" > JavaScript< / label > < label for = "__tabbed_1_6" > TypeScript< / label > < label for = "__tabbed_1_7" > C< / label > < label for = "__tabbed_1_8" > C#< / label > < label for = "__tabbed_1_9" > Swift< / label > < label for = "__tabbed_1_10" > Zig< / label > < / div >
< div class = "tabbed-content" >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.java< / span > < pre > < span > < / span > < code > < a id = "__codelineno-0-1" name = "__codelineno-0-1" href = "#__codelineno-0-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-0-2" name = "__codelineno-0-2" href = "#__codelineno-0-2" > < / a > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "n" > Integer< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-0-3" name = "__codelineno-0-3" href = "#__codelineno-0-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-0-4" name = "__codelineno-0-4" href = "#__codelineno-0-4" > < / a > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "w" > < / span > < span class = "n" > LinkedList< / span > < span class = "o" > < > < / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > {{< / span > < span class = "w" > < / span > < span class = "n" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "p" > }};< / span >
< a id = "__codelineno-0-5" name = "__codelineno-0-5" href = "#__codelineno-0-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-0-6" name = "__codelineno-0-6" href = "#__codelineno-0-6" > < / a > < span class = "w" > < / span > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "n" > Integer< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "w" > < / span > < span class = "n" > ArrayList< / span > < span class = "o" > < > < / span > < span class = "p" > ();< / span >
< a id = "__codelineno-0-7" name = "__codelineno-0-7" href = "#__codelineno-0-7" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > isEmpty< / span > < span class = "p" > ())< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-0-8" name = "__codelineno-0-8" href = "#__codelineno-0-8" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > poll< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-0-9" name = "__codelineno-0-9" href = "#__codelineno-0-9" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-0-10" name = "__codelineno-0-10" href = "#__codelineno-0-10" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-0-11" name = "__codelineno-0-11" href = "#__codelineno-0-11" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-0-12" name = "__codelineno-0-12" href = "#__codelineno-0-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-0-13" name = "__codelineno-0-13" href = "#__codelineno-0-13" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "na" > offer< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-0-14" name = "__codelineno-0-14" href = "#__codelineno-0-14" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-0-15" name = "__codelineno-0-15" href = "#__codelineno-0-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-0-16" name = "__codelineno-0-16" href = "#__codelineno-0-16" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.cpp< / span > < pre > < span > < / span > < code > < a id = "__codelineno-1-1" name = "__codelineno-1-1" href = "#__codelineno-1-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-1-2" name = "__codelineno-1-2" href = "#__codelineno-1-2" > < / a > < span class = "n" > vector< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-1-3" name = "__codelineno-1-3" href = "#__codelineno-1-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-1-4" name = "__codelineno-1-4" href = "#__codelineno-1-4" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *> < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-5" name = "__codelineno-1-5" href = "#__codelineno-1-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-1-6" name = "__codelineno-1-6" href = "#__codelineno-1-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-1-7" name = "__codelineno-1-7" href = "#__codelineno-1-7" > < / a > < span class = "w" > < / span > < span class = "n" > vector< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-8" name = "__codelineno-1-8" href = "#__codelineno-1-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > empty< / span > < span class = "p" > ())< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-1-9" name = "__codelineno-1-9" href = "#__codelineno-1-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > front< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-1-10" name = "__codelineno-1-10" href = "#__codelineno-1-10" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > pop< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-1-11" name = "__codelineno-1-11" href = "#__codelineno-1-11" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-1-12" name = "__codelineno-1-12" href = "#__codelineno-1-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-1-13" name = "__codelineno-1-13" href = "#__codelineno-1-13" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-1-14" name = "__codelineno-1-14" href = "#__codelineno-1-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-1-15" name = "__codelineno-1-15" href = "#__codelineno-1-15" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > push< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-1-16" name = "__codelineno-1-16" href = "#__codelineno-1-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-1-17" name = "__codelineno-1-17" href = "#__codelineno-1-17" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-1-18" name = "__codelineno-1-18" href = "#__codelineno-1-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.py< / span > < pre > < span > < / span > < code > < a id = "__codelineno-2-1" name = "__codelineno-2-1" href = "#__codelineno-2-1" > < / a > < span class = "k" > def< / span > < span class = "nf" > level_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > )< / span > < span class = "o" > -> < / span > < span class = "nb" > list< / span > < span class = "p" > [< / span > < span class = "nb" > int< / span > < span class = "p" > ]:< / span >
< a id = "__codelineno-2-2" name = "__codelineno-2-2" href = "#__codelineno-2-2" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 层序遍历" " " < / span >
< a id = "__codelineno-2-3" name = "__codelineno-2-3" href = "#__codelineno-2-3" > < / a > < span class = "c1" > # 初始化队列，加入根节点< / span >
< a id = "__codelineno-2-4" name = "__codelineno-2-4" href = "#__codelineno-2-4" > < / a > < span class = "n" > queue< / span > < span class = "p" > :< / span > < span class = "n" > deque< / span > < span class = "p" > [< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ]< / span > < span class = "o" > =< / span > < span class = "n" > deque< / span > < span class = "p" > ()< / span >
< a id = "__codelineno-2-5" name = "__codelineno-2-5" href = "#__codelineno-2-5" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > )< / span >
< a id = "__codelineno-2-6" name = "__codelineno-2-6" href = "#__codelineno-2-6" > < / a > < span class = "c1" > # 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-2-7" name = "__codelineno-2-7" href = "#__codelineno-2-7" > < / a > < span class = "n" > res< / span > < span class = "o" > =< / span > < span class = "p" > []< / span >
< a id = "__codelineno-2-8" name = "__codelineno-2-8" href = "#__codelineno-2-8" > < / a > < span class = "k" > while< / span > < span class = "n" > queue< / span > < span class = "p" > :< / span >
< a id = "__codelineno-2-9" name = "__codelineno-2-9" href = "#__codelineno-2-9" > < / a > < span class = "n" > node< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > =< / span > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > popleft< / span > < span class = "p" > ()< / span > < span class = "c1" > # 队列出队< / span >
< a id = "__codelineno-2-10" name = "__codelineno-2-10" href = "#__codelineno-2-10" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span > < span class = "c1" > # 保存节点值< / span >
< a id = "__codelineno-2-11" name = "__codelineno-2-11" href = "#__codelineno-2-11" > < / a > < span class = "k" > if< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "ow" > is< / span > < span class = "ow" > not< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-2-12" name = "__codelineno-2-12" href = "#__codelineno-2-12" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span > < span class = "c1" > # 左子节点入队< / span >
< a id = "__codelineno-2-13" name = "__codelineno-2-13" href = "#__codelineno-2-13" > < / a > < span class = "k" > if< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "ow" > is< / span > < span class = "ow" > not< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-2-14" name = "__codelineno-2-14" href = "#__codelineno-2-14" > < / a > < span class = "n" > queue< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span > < span class = "c1" > # 右子节点入队< / span >
< a id = "__codelineno-2-15" name = "__codelineno-2-15" href = "#__codelineno-2-15" > < / a > < span class = "k" > return< / span > < span class = "n" > res< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.go< / span > < pre > < span > < / span > < code > < a id = "__codelineno-3-1" name = "__codelineno-3-1" href = "#__codelineno-3-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-3-2" name = "__codelineno-3-2" href = "#__codelineno-3-2" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > []< / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-3" name = "__codelineno-3-3" href = "#__codelineno-3-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-3-4" name = "__codelineno-3-4" href = "#__codelineno-3-4" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > New< / span > < span class = "p" > ()< / span >
< a id = "__codelineno-3-5" name = "__codelineno-3-5" href = "#__codelineno-3-5" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-6" name = "__codelineno-3-6" href = "#__codelineno-3-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个切片，用于保存遍历序列< / span >
< a id = "__codelineno-3-7" name = "__codelineno-3-7" href = "#__codelineno-3-7" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nb" > make< / span > < span class = "p" > ([]< / span > < span class = "kt" > int< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-8" name = "__codelineno-3-8" href = "#__codelineno-3-8" > < / a > < span class = "w" > < / span > < span class = "k" > for< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Len< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "p" > > < / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-9" name = "__codelineno-3-9" href = "#__codelineno-3-9" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-3-10" name = "__codelineno-3-10" href = "#__codelineno-3-10" > < / a > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > :=< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Remove< / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > Front< / span > < span class = "p" > ()).(< / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-11" name = "__codelineno-3-11" href = "#__codelineno-3-11" > < / a > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-3-12" name = "__codelineno-3-12" href = "#__codelineno-3-12" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-13" name = "__codelineno-3-13" href = "#__codelineno-3-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-14" name = "__codelineno-3-14" href = "#__codelineno-3-14" > < / a > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-3-15" name = "__codelineno-3-15" href = "#__codelineno-3-15" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-16" name = "__codelineno-3-16" href = "#__codelineno-3-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-3-17" name = "__codelineno-3-17" href = "#__codelineno-3-17" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-3-18" name = "__codelineno-3-18" href = "#__codelineno-3-18" > < / a > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-3-19" name = "__codelineno-3-19" href = "#__codelineno-3-19" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > PushBack< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-3-20" name = "__codelineno-3-20" href = "#__codelineno-3-20" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-3-21" name = "__codelineno-3-21" href = "#__codelineno-3-21" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-3-22" name = "__codelineno-3-22" href = "#__codelineno-3-22" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > nums< / span >
< a id = "__codelineno-3-23" name = "__codelineno-3-23" href = "#__codelineno-3-23" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.js< / span > < pre > < span > < / span > < code > < a id = "__codelineno-4-1" name = "__codelineno-4-1" href = "#__codelineno-4-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-4-2" name = "__codelineno-4-2" href = "#__codelineno-4-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-3" name = "__codelineno-4-3" href = "#__codelineno-4-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-4-4" name = "__codelineno-4-4" href = "#__codelineno-4-4" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [< / span > < span class = "nx" > root< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-4-5" name = "__codelineno-4-5" href = "#__codelineno-4-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-4-6" name = "__codelineno-4-6" href = "#__codelineno-4-6" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-4-7" name = "__codelineno-4-7" href = "#__codelineno-4-7" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > length< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-4-8" name = "__codelineno-4-8" href = "#__codelineno-4-8" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > shift< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-4-9" name = "__codelineno-4-9" href = "#__codelineno-4-9" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-4-10" name = "__codelineno-4-10" href = "#__codelineno-4-10" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-4-11" name = "__codelineno-4-11" href = "#__codelineno-4-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-4-12" name = "__codelineno-4-12" href = "#__codelineno-4-12" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-4-13" name = "__codelineno-4-13" href = "#__codelineno-4-13" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-4-14" name = "__codelineno-4-14" href = "#__codelineno-4-14" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.ts< / span > < pre > < span > < / span > < code > < a id = "__codelineno-5-1" name = "__codelineno-5-1" href = "#__codelineno-5-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-5-2" name = "__codelineno-5-2" href = "#__codelineno-5-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > levelOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > number< / span > < span class = "p" > []< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-3" name = "__codelineno-5-3" href = "#__codelineno-5-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-5-4" name = "__codelineno-5-4" href = "#__codelineno-5-4" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [< / span > < span class = "nx" > root< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-5-5" name = "__codelineno-5-5" href = "#__codelineno-5-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-5-6" name = "__codelineno-5-6" href = "#__codelineno-5-6" > < / a > < span class = "w" > < / span > < span class = "kd" > const< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > number< / span > < span class = "p" > []< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > [];< / span >
< a id = "__codelineno-5-7" name = "__codelineno-5-7" href = "#__codelineno-5-7" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > length< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-8" name = "__codelineno-5-8" href = "#__codelineno-5-8" > < / a > < span class = "w" > < / span > < span class = "kd" > let< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > shift< / span > < span class = "p" > ()< / span > < span class = "w" > < / span > < span class = "kr" > as< / span > < span class = "w" > < / span > < span class = "nx" > TreeNode< / span > < span class = "p" > ;< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-5-9" name = "__codelineno-5-9" href = "#__codelineno-5-9" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-5-10" name = "__codelineno-5-10" href = "#__codelineno-5-10" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-11" name = "__codelineno-5-11" href = "#__codelineno-5-11" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-5-12" name = "__codelineno-5-12" href = "#__codelineno-5-12" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-5-13" name = "__codelineno-5-13" href = "#__codelineno-5-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-5-14" name = "__codelineno-5-14" href = "#__codelineno-5-14" > < / a > < span class = "w" > < / span > < span class = "nx" > queue< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-5-15" name = "__codelineno-5-15" href = "#__codelineno-5-15" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-5-16" name = "__codelineno-5-16" href = "#__codelineno-5-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-5-17" name = "__codelineno-5-17" href = "#__codelineno-5-17" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-5-18" name = "__codelineno-5-18" href = "#__codelineno-5-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.c< / span > < pre > < span > < / span > < code > < a id = "__codelineno-6-1" name = "__codelineno-6-1" href = "#__codelineno-6-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-6-2" name = "__codelineno-6-2" href = "#__codelineno-6-2" > < / a > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-3" name = "__codelineno-6-3" href = "#__codelineno-6-3" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助队列 */< / span >
< a id = "__codelineno-6-4" name = "__codelineno-6-4" href = "#__codelineno-6-4" > < / a > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "n" > front< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-5" name = "__codelineno-6-5" href = "#__codelineno-6-5" > < / a > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > arr< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-6" name = "__codelineno-6-6" href = "#__codelineno-6-6" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > node< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-7" name = "__codelineno-6-7" href = "#__codelineno-6-7" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > **< / span > < span class = "n" > queue< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-8" name = "__codelineno-6-8" href = "#__codelineno-6-8" > < / a >
< a id = "__codelineno-6-9" name = "__codelineno-6-9" href = "#__codelineno-6-9" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助队列 */< / span >
< a id = "__codelineno-6-10" name = "__codelineno-6-10" href = "#__codelineno-6-10" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > **< / span > < span class = "p" > )< / span > < span class = "n" > malloc< / span > < span class = "p" > (< / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "n" > MAX_NODE_SIZE< / span > < span class = "p" > );< / span >
< a id = "__codelineno-6-11" name = "__codelineno-6-11" href = "#__codelineno-6-11" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列指针< / span >
< a id = "__codelineno-6-12" name = "__codelineno-6-12" href = "#__codelineno-6-12" > < / a > < span class = "w" > < / span > < span class = "n" > front< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-13" name = "__codelineno-6-13" href = "#__codelineno-6-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 加入根节点< / span >
< a id = "__codelineno-6-14" name = "__codelineno-6-14" href = "#__codelineno-6-14" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-15" name = "__codelineno-6-15" href = "#__codelineno-6-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-6-16" name = "__codelineno-6-16" href = "#__codelineno-6-16" > < / a > < span class = "w" > < / span > < span class = "cm" > /* 辅助数组 */< / span >
< a id = "__codelineno-6-17" name = "__codelineno-6-17" href = "#__codelineno-6-17" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "p" > )< / span > < span class = "n" > malloc< / span > < span class = "p" > (< / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "n" > MAX_NODE_SIZE< / span > < span class = "p" > );< / span >
< a id = "__codelineno-6-18" name = "__codelineno-6-18" href = "#__codelineno-6-18" > < / a > < span class = "w" > < / span > < span class = "c1" > // 数组指针< / span >
< a id = "__codelineno-6-19" name = "__codelineno-6-19" href = "#__codelineno-6-19" > < / a > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-20" name = "__codelineno-6-20" href = "#__codelineno-6-20" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > front< / span > < span class = "w" > < / span > < span class = "o" > < < / span > < span class = "w" > < / span > < span class = "n" > rear< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-21" name = "__codelineno-6-21" href = "#__codelineno-6-21" > < / a > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-6-22" name = "__codelineno-6-22" href = "#__codelineno-6-22" > < / a > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > front< / span > < span class = "o" > ++< / span > < span class = "p" > ];< / span >
< a id = "__codelineno-6-23" name = "__codelineno-6-23" href = "#__codelineno-6-23" > < / a > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-6-24" name = "__codelineno-6-24" href = "#__codelineno-6-24" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [< / span > < span class = "n" > index< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-25" name = "__codelineno-6-25" href = "#__codelineno-6-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-26" name = "__codelineno-6-26" href = "#__codelineno-6-26" > < / a > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-6-27" name = "__codelineno-6-27" href = "#__codelineno-6-27" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-28" name = "__codelineno-6-28" href = "#__codelineno-6-28" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-6-29" name = "__codelineno-6-29" href = "#__codelineno-6-29" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-6-30" name = "__codelineno-6-30" href = "#__codelineno-6-30" > < / a > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-6-31" name = "__codelineno-6-31" href = "#__codelineno-6-31" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > [< / span > < span class = "n" > rear< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-32" name = "__codelineno-6-32" href = "#__codelineno-6-32" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-6-33" name = "__codelineno-6-33" href = "#__codelineno-6-33" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-6-34" name = "__codelineno-6-34" href = "#__codelineno-6-34" > < / a > < span class = "w" > < / span > < span class = "c1" > // 更新数组长度的值< / span >
< a id = "__codelineno-6-35" name = "__codelineno-6-35" href = "#__codelineno-6-35" > < / a > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > index< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-36" name = "__codelineno-6-36" href = "#__codelineno-6-36" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > realloc< / span > < span class = "p" > (< / span > < span class = "n" > arr< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "k" > sizeof< / span > < span class = "p" > (< / span > < span class = "kt" > int< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > ));< / span >
< a id = "__codelineno-6-37" name = "__codelineno-6-37" href = "#__codelineno-6-37" > < / a >
< a id = "__codelineno-6-38" name = "__codelineno-6-38" href = "#__codelineno-6-38" > < / a > < span class = "w" > < / span > < span class = "c1" > // 释放辅助数组空间< / span >
< a id = "__codelineno-6-39" name = "__codelineno-6-39" href = "#__codelineno-6-39" > < / a > < span class = "w" > < / span > < span class = "n" > free< / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > );< / span >
< a id = "__codelineno-6-40" name = "__codelineno-6-40" href = "#__codelineno-6-40" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-6-41" name = "__codelineno-6-41" href = "#__codelineno-6-41" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.cs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-7-1" name = "__codelineno-7-1" href = "#__codelineno-7-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-7-2" name = "__codelineno-7-2" href = "#__codelineno-7-2" > < / a > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-3" name = "__codelineno-7-3" href = "#__codelineno-7-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-7-4" name = "__codelineno-7-4" href = "#__codelineno-7-4" > < / a > < span class = "w" > < / span > < span class = "n" > Queue< / span > < span class = "o" > < < / span > < span class = "n" > TreeNode< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-7-5" name = "__codelineno-7-5" href = "#__codelineno-7-5" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > );< / span >
< a id = "__codelineno-7-6" name = "__codelineno-7-6" href = "#__codelineno-7-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-7-7" name = "__codelineno-7-7" href = "#__codelineno-7-7" > < / a > < span class = "w" > < / span > < span class = "n" > List< / span > < span class = "o" > < < / span > < span class = "kt" > int< / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > new< / span > < span class = "p" > ();< / span >
< a id = "__codelineno-7-8" name = "__codelineno-7-8" href = "#__codelineno-7-8" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Count< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "m" > 0< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-7-9" name = "__codelineno-7-9" href = "#__codelineno-7-9" > < / a > < span class = "w" > < / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Dequeue< / span > < span class = "p" > ();< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-7-10" name = "__codelineno-7-10" href = "#__codelineno-7-10" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-7-11" name = "__codelineno-7-11" href = "#__codelineno-7-11" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-7-12" name = "__codelineno-7-12" href = "#__codelineno-7-12" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-7-13" name = "__codelineno-7-13" href = "#__codelineno-7-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-7-14" name = "__codelineno-7-14" href = "#__codelineno-7-14" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > Enqueue< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-7-15" name = "__codelineno-7-15" href = "#__codelineno-7-15" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-7-16" name = "__codelineno-7-16" href = "#__codelineno-7-16" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-7-17" name = "__codelineno-7-17" href = "#__codelineno-7-17" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.swift< / span > < pre > < span > < / span > < code > < a id = "__codelineno-8-1" name = "__codelineno-8-1" href = "#__codelineno-8-1" > < / a > < span class = "cm" > /* 层序遍历 */< / span >
< a id = "__codelineno-8-2" name = "__codelineno-8-2" href = "#__codelineno-8-2" > < / a > < span class = "kd" > func< / span > < span class = "nf" > levelOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > )< / span > < span class = "p" > -> < / span > < span class = "p" > [< / span > < span class = "nb" > Int< / span > < span class = "p" > ]< / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-3" name = "__codelineno-8-3" href = "#__codelineno-8-3" > < / a > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-8-4" name = "__codelineno-8-4" href = "#__codelineno-8-4" > < / a > < span class = "kd" > var< / span > < span class = "nv" > queue< / span > < span class = "p" > :< / span > < span class = "p" > [< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ]< / span > < span class = "p" > =< / span > < span class = "p" > [< / span > < span class = "n" > root< / span > < span class = "p" > ]< / span >
< a id = "__codelineno-8-5" name = "__codelineno-8-5" href = "#__codelineno-8-5" > < / a > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-8-6" name = "__codelineno-8-6" href = "#__codelineno-8-6" > < / a > < span class = "kd" > var< / span > < span class = "nv" > list< / span > < span class = "p" > :< / span > < span class = "p" > [< / span > < span class = "nb" > Int< / span > < span class = "p" > ]< / span > < span class = "p" > =< / span > < span class = "p" > []< / span >
< a id = "__codelineno-8-7" name = "__codelineno-8-7" href = "#__codelineno-8-7" > < / a > < span class = "k" > while< / span > < span class = "o" > !< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "bp" > isEmpty< / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-8" name = "__codelineno-8-8" href = "#__codelineno-8-8" > < / a > < span class = "kd" > let< / span > < span class = "nv" > node< / span > < span class = "p" > =< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > removeFirst< / span > < span class = "p" > ()< / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-8-9" name = "__codelineno-8-9" href = "#__codelineno-8-9" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-8-10" name = "__codelineno-8-10" href = "#__codelineno-8-10" > < / a > < span class = "k" > if< / span > < span class = "kd" > let< / span > < span class = "nv" > left< / span > < span class = "p" > =< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-11" name = "__codelineno-8-11" href = "#__codelineno-8-11" > < / a > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-8-12" name = "__codelineno-8-12" href = "#__codelineno-8-12" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-8-13" name = "__codelineno-8-13" href = "#__codelineno-8-13" > < / a > < span class = "k" > if< / span > < span class = "kd" > let< / span > < span class = "nv" > right< / span > < span class = "p" > =< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > {< / span >
< a id = "__codelineno-8-14" name = "__codelineno-8-14" href = "#__codelineno-8-14" > < / a > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-8-15" name = "__codelineno-8-15" href = "#__codelineno-8-15" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-8-16" name = "__codelineno-8-16" href = "#__codelineno-8-16" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-8-17" name = "__codelineno-8-17" href = "#__codelineno-8-17" > < / a > < span class = "k" > return< / span > < span class = "n" > list< / span >
< a id = "__codelineno-8-18" name = "__codelineno-8-18" href = "#__codelineno-8-18" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_bfs.zig< / span > < pre > < span > < / span > < code > < a id = "__codelineno-9-1" name = "__codelineno-9-1" href = "#__codelineno-9-1" > < / a > < span class = "c1" > // 层序遍历< / span >
< a id = "__codelineno-9-2" name = "__codelineno-9-2" href = "#__codelineno-9-2" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > levelOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > mem< / span > < span class = "p" > .< / span > < span class = "n" > Allocator< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > ArrayList< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-3" name = "__codelineno-9-3" href = "#__codelineno-9-3" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化队列，加入根节点< / span >
< a id = "__codelineno-9-4" name = "__codelineno-9-4" href = "#__codelineno-9-4" > < / a > < span class = "w" > < / span > < span class = "kr" > const< / span > < span class = "w" > < / span > < span class = "n" > L< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > TailQueue< / span > < span class = "p" > (< / span > < span class = "o" > *< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ));< / span >
< a id = "__codelineno-9-5" name = "__codelineno-9-5" href = "#__codelineno-9-5" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > L< / span > < span class = "p" > {};< / span >
< a id = "__codelineno-9-6" name = "__codelineno-9-6" href = "#__codelineno-9-6" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > root_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-9-7" name = "__codelineno-9-7" href = "#__codelineno-9-7" > < / a > < span class = "w" > < / span > < span class = "n" > root_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-9-8" name = "__codelineno-9-8" href = "#__codelineno-9-8" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span >
< a id = "__codelineno-9-9" name = "__codelineno-9-9" href = "#__codelineno-9-9" > < / a > < span class = "w" > < / span > < span class = "c1" > // 初始化一个列表，用于保存遍历序列< / span >
< a id = "__codelineno-9-10" name = "__codelineno-9-10" href = "#__codelineno-9-10" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > ArrayList< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ).< / span > < span class = "n" > init< / span > < span class = "p" > (< / span > < span class = "n" > std< / span > < span class = "p" > .< / span > < span class = "n" > heap< / span > < span class = "p" > .< / span > < span class = "n" > page_allocator< / span > < span class = "p" > );< / span >
< a id = "__codelineno-9-11" name = "__codelineno-9-11" href = "#__codelineno-9-11" > < / a > < span class = "w" > < / span > < span class = "k" > while< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > len< / span > < span class = "w" > < / span > < span class = "o" > > < / span > < span class = "w" > < / span > < span class = "mi" > 0< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-12" name = "__codelineno-9-12" href = "#__codelineno-9-12" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > queue_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > popFirst< / span > < span class = "p" > ().< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span > < span class = "w" > < / span > < span class = "c1" > // 队列出队< / span >
< a id = "__codelineno-9-13" name = "__codelineno-9-13" href = "#__codelineno-9-13" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > queue_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-9-14" name = "__codelineno-9-14" href = "#__codelineno-9-14" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 保存节点值< / span >
< a id = "__codelineno-9-15" name = "__codelineno-9-15" href = "#__codelineno-9-15" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-16" name = "__codelineno-9-16" href = "#__codelineno-9-16" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-9-17" name = "__codelineno-9-17" href = "#__codelineno-9-17" > < / a > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-9-18" name = "__codelineno-9-18" href = "#__codelineno-9-18" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > tmp_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 左子节点入队< / span >
< a id = "__codelineno-9-19" name = "__codelineno-9-19" href = "#__codelineno-9-19" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-9-20" name = "__codelineno-9-20" href = "#__codelineno-9-20" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "w" > < / span > < span class = "o" > !=< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-9-21" name = "__codelineno-9-21" href = "#__codelineno-9-21" > < / a > < span class = "w" > < / span > < span class = "kr" > var< / span > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > mem_allocator< / span > < span class = "p" > .< / span > < span class = "n" > create< / span > < span class = "p" > (< / span > < span class = "n" > L< / span > < span class = "p" > .< / span > < span class = "n" > Node< / span > < span class = "p" > );< / span >
< a id = "__codelineno-9-22" name = "__codelineno-9-22" href = "#__codelineno-9-22" > < / a > < span class = "w" > < / span > < span class = "n" > tmp_node< / span > < span class = "p" > .< / span > < span class = "n" > data< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > node< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-9-23" name = "__codelineno-9-23" href = "#__codelineno-9-23" > < / a > < span class = "w" > < / span > < span class = "n" > queue< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > tmp_node< / span > < span class = "p" > );< / span > < span class = "w" > < / span > < span class = "c1" > // 右子节点入队< / span >
< a id = "__codelineno-9-24" name = "__codelineno-9-24" href = "#__codelineno-9-24" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span > < span class = "w" > < / span >
< a id = "__codelineno-9-25" name = "__codelineno-9-25" href = "#__codelineno-9-25" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-9-26" name = "__codelineno-9-26" href = "#__codelineno-9-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-9-27" name = "__codelineno-9-27" href = "#__codelineno-9-27" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< / div >
< / div >
< h3 id = "_2" > 复杂度分析< a class = "headerlink" href = "#_2" title = "Permanent link" > ¶ < / a > < / h3 >
< p > < strong > 时间复杂度< / strong > ：所有节点被访问一次，使用 < span class = "arithmatex" > \(O(n)\)< / span > 时间，其中 < span class = "arithmatex" > \(n\)< / span > 为节点数量。< / p >
< p > < strong > 空间复杂度< / strong > ：在最差情况下，即满二叉树时，遍历到最底层之前，队列中最多同时存在 < span class = "arithmatex" > \(\frac{n + 1}{2}\)< / span > 个节点，占用 < span class = "arithmatex" > \(O(n)\)< / span > 空间。< / p >
< h2 id = "722" > 7.2.2. 前序、中序、后序遍历< a class = "headerlink" href = "#722" title = "Permanent link" > ¶ < / a > < / h2 >
< p > 相应地，前序、中序和后序遍历都属于「深度优先遍历 Depth-First Traversal」， ， < / p >
< p > 如下图所示，左侧是深度优先遍历的示意图，右上方是对应的递归实现代码。深度优先遍历就像是绕着整个二叉树的外围“走”一圈，在这个过程中，在每个节点都会遇到三个位置，分别对应前序遍历、中序遍历和后序遍历。< / p >
< p > < img alt = "二叉搜索树的前、中、后序遍历" src = "../binary_tree_traversal.assets/binary_tree_dfs.png" / > < / p >
< p align = "center" > Fig. 二叉搜索树的前、中、后序遍历 < / p >
< div class = "center-table" >
< table >
< thead >
< tr >
< th > 位置< / th >
< th > 含义< / th >
< th > 此处访问节点时对应< / th >
< / tr >
< / thead >
< tbody >
< tr >
< td > 橙色圆圈处< / td >
< td > 刚进入此节点，即将访问该节点的左子树< / td >
< td > 前序遍历 Pre-Order Traversal< / td >
< / tr >
< tr >
< td > 蓝色圆圈处< / td >
< td > 已访问完左子树，即将访问右子树< / td >
< td > 中序遍历 In-Order Traversal< / td >
< / tr >
< tr >
< td > 紫色圆圈处< / td >
< td > 已访问完左子树和右子树，即将返回< / td >
< td > 后序遍历 Post-Order Traversal< / td >
< / tr >
< / tbody >
< / table >
< / div >
< h3 id = "_3" > 算法实现< a class = "headerlink" href = "#_3" title = "Permanent link" > ¶ < / a > < / h3 >
< div class = "tabbed-set tabbed-alternate" data-tabs = "2:10" > < input checked = "checked" id = "__tabbed_2_1" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_2" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_3" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_4" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_5" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_6" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_7" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_8" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_9" name = "__tabbed_2" type = "radio" / > < input id = "__tabbed_2_10" name = "__tabbed_2" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_2_1" > Java< / label > < label for = "__tabbed_2_2" > C++< / label > < label for = "__tabbed_2_3" > Python< / label > < label for = "__tabbed_2_4" > Go< / label > < label for = "__tabbed_2_5" > JavaScript< / label > < label for = "__tabbed_2_6" > TypeScript< / label > < label for = "__tabbed_2_7" > C< / label > < label for = "__tabbed_2_8" > C#< / label > < label for = "__tabbed_2_9" > Swift< / label > < label for = "__tabbed_2_10" > Zig< / label > < / div >
< div class = "tabbed-content" >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.java< / span > < pre > < span > < / span > < code > < a id = "__codelineno-10-1" name = "__codelineno-10-1" href = "#__codelineno-10-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-10-2" name = "__codelineno-10-2" href = "#__codelineno-10-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-3" name = "__codelineno-10-3" href = "#__codelineno-10-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-10-4" name = "__codelineno-10-4" href = "#__codelineno-10-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-5" name = "__codelineno-10-5" href = "#__codelineno-10-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-10-6" name = "__codelineno-10-6" href = "#__codelineno-10-6" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-7" name = "__codelineno-10-7" href = "#__codelineno-10-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-8" name = "__codelineno-10-8" href = "#__codelineno-10-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-9" name = "__codelineno-10-9" href = "#__codelineno-10-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-10-10" name = "__codelineno-10-10" href = "#__codelineno-10-10" > < / a >
< a id = "__codelineno-10-11" name = "__codelineno-10-11" href = "#__codelineno-10-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-10-12" name = "__codelineno-10-12" href = "#__codelineno-10-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-13" name = "__codelineno-10-13" href = "#__codelineno-10-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-10-14" name = "__codelineno-10-14" href = "#__codelineno-10-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-15" name = "__codelineno-10-15" href = "#__codelineno-10-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-10-16" name = "__codelineno-10-16" href = "#__codelineno-10-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-17" name = "__codelineno-10-17" href = "#__codelineno-10-17" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-18" name = "__codelineno-10-18" href = "#__codelineno-10-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-19" name = "__codelineno-10-19" href = "#__codelineno-10-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-10-20" name = "__codelineno-10-20" href = "#__codelineno-10-20" > < / a >
< a id = "__codelineno-10-21" name = "__codelineno-10-21" href = "#__codelineno-10-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-10-22" name = "__codelineno-10-22" href = "#__codelineno-10-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-10-23" name = "__codelineno-10-23" href = "#__codelineno-10-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span >
< a id = "__codelineno-10-24" name = "__codelineno-10-24" href = "#__codelineno-10-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-10-25" name = "__codelineno-10-25" href = "#__codelineno-10-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-10-26" name = "__codelineno-10-26" href = "#__codelineno-10-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-27" name = "__codelineno-10-27" href = "#__codelineno-10-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-28" name = "__codelineno-10-28" href = "#__codelineno-10-28" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "na" > add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "na" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-10-29" name = "__codelineno-10-29" href = "#__codelineno-10-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.cpp< / span > < pre > < span > < / span > < code > < a id = "__codelineno-11-1" name = "__codelineno-11-1" href = "#__codelineno-11-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-11-2" name = "__codelineno-11-2" href = "#__codelineno-11-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-11-3" name = "__codelineno-11-3" href = "#__codelineno-11-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-11-4" name = "__codelineno-11-4" href = "#__codelineno-11-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-11-5" name = "__codelineno-11-5" href = "#__codelineno-11-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-11-6" name = "__codelineno-11-6" href = "#__codelineno-11-6" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-7" name = "__codelineno-11-7" href = "#__codelineno-11-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-8" name = "__codelineno-11-8" href = "#__codelineno-11-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-9" name = "__codelineno-11-9" href = "#__codelineno-11-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-11-10" name = "__codelineno-11-10" href = "#__codelineno-11-10" > < / a >
< a id = "__codelineno-11-11" name = "__codelineno-11-11" href = "#__codelineno-11-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-11-12" name = "__codelineno-11-12" href = "#__codelineno-11-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-11-13" name = "__codelineno-11-13" href = "#__codelineno-11-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-11-14" name = "__codelineno-11-14" href = "#__codelineno-11-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-11-15" name = "__codelineno-11-15" href = "#__codelineno-11-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-11-16" name = "__codelineno-11-16" href = "#__codelineno-11-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-17" name = "__codelineno-11-17" href = "#__codelineno-11-17" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-18" name = "__codelineno-11-18" href = "#__codelineno-11-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-19" name = "__codelineno-11-19" href = "#__codelineno-11-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-11-20" name = "__codelineno-11-20" href = "#__codelineno-11-20" > < / a >
< a id = "__codelineno-11-21" name = "__codelineno-11-21" href = "#__codelineno-11-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-11-22" name = "__codelineno-11-22" href = "#__codelineno-11-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-11-23" name = "__codelineno-11-23" href = "#__codelineno-11-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > nullptr< / span > < span class = "p" > )< / span >
< a id = "__codelineno-11-24" name = "__codelineno-11-24" href = "#__codelineno-11-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-11-25" name = "__codelineno-11-25" href = "#__codelineno-11-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-11-26" name = "__codelineno-11-26" href = "#__codelineno-11-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-27" name = "__codelineno-11-27" href = "#__codelineno-11-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-28" name = "__codelineno-11-28" href = "#__codelineno-11-28" > < / a > < span class = "w" > < / span > < span class = "n" > vec< / span > < span class = "p" > .< / span > < span class = "n" > push_back< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-11-29" name = "__codelineno-11-29" href = "#__codelineno-11-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.py< / span > < pre > < span > < / span > < code > < a id = "__codelineno-12-1" name = "__codelineno-12-1" href = "#__codelineno-12-1" > < / a > < span class = "k" > def< / span > < span class = "nf" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > )< / span > < span class = "o" > -> < / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-2" name = "__codelineno-12-2" href = "#__codelineno-12-2" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 前序遍历" " " < / span >
< a id = "__codelineno-12-3" name = "__codelineno-12-3" href = "#__codelineno-12-3" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-4" name = "__codelineno-12-4" href = "#__codelineno-12-4" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-12-5" name = "__codelineno-12-5" href = "#__codelineno-12-5" > < / a > < span class = "c1" > # 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-12-6" name = "__codelineno-12-6" href = "#__codelineno-12-6" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-7" name = "__codelineno-12-7" href = "#__codelineno-12-7" > < / a > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-8" name = "__codelineno-12-8" href = "#__codelineno-12-8" > < / a > < span class = "n" > pre_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-9" name = "__codelineno-12-9" href = "#__codelineno-12-9" > < / a >
< a id = "__codelineno-12-10" name = "__codelineno-12-10" href = "#__codelineno-12-10" > < / a > < span class = "k" > def< / span > < span class = "nf" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > )< / span > < span class = "o" > -> < / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-11" name = "__codelineno-12-11" href = "#__codelineno-12-11" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 中序遍历" " " < / span >
< a id = "__codelineno-12-12" name = "__codelineno-12-12" href = "#__codelineno-12-12" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-13" name = "__codelineno-12-13" href = "#__codelineno-12-13" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-12-14" name = "__codelineno-12-14" href = "#__codelineno-12-14" > < / a > < span class = "c1" > # 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-12-15" name = "__codelineno-12-15" href = "#__codelineno-12-15" > < / a > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-16" name = "__codelineno-12-16" href = "#__codelineno-12-16" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-17" name = "__codelineno-12-17" href = "#__codelineno-12-17" > < / a > < span class = "n" > in_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-18" name = "__codelineno-12-18" href = "#__codelineno-12-18" > < / a >
< a id = "__codelineno-12-19" name = "__codelineno-12-19" href = "#__codelineno-12-19" > < / a > < span class = "k" > def< / span > < span class = "nf" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "o" > |< / span > < span class = "kc" > None< / span > < span class = "p" > )< / span > < span class = "o" > -> < / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-20" name = "__codelineno-12-20" href = "#__codelineno-12-20" > < / a > < span class = "w" > < / span > < span class = "sd" > " " " 后序遍历" " " < / span >
< a id = "__codelineno-12-21" name = "__codelineno-12-21" href = "#__codelineno-12-21" > < / a > < span class = "k" > if< / span > < span class = "n" > root< / span > < span class = "ow" > is< / span > < span class = "kc" > None< / span > < span class = "p" > :< / span >
< a id = "__codelineno-12-22" name = "__codelineno-12-22" href = "#__codelineno-12-22" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-12-23" name = "__codelineno-12-23" href = "#__codelineno-12-23" > < / a > < span class = "c1" > # 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-12-24" name = "__codelineno-12-24" href = "#__codelineno-12-24" > < / a > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-25" name = "__codelineno-12-25" href = "#__codelineno-12-25" > < / a > < span class = "n" > post_order< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > =< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-12-26" name = "__codelineno-12-26" href = "#__codelineno-12-26" > < / a > < span class = "n" > res< / span > < span class = "o" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.go< / span > < pre > < span > < / span > < code > < a id = "__codelineno-13-1" name = "__codelineno-13-1" href = "#__codelineno-13-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-13-2" name = "__codelineno-13-2" href = "#__codelineno-13-2" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-3" name = "__codelineno-13-3" href = "#__codelineno-13-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-4" name = "__codelineno-13-4" href = "#__codelineno-13-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-13-5" name = "__codelineno-13-5" href = "#__codelineno-13-5" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-13-6" name = "__codelineno-13-6" href = "#__codelineno-13-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-13-7" name = "__codelineno-13-7" href = "#__codelineno-13-7" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-8" name = "__codelineno-13-8" href = "#__codelineno-13-8" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-9" name = "__codelineno-13-9" href = "#__codelineno-13-9" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-10" name = "__codelineno-13-10" href = "#__codelineno-13-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-13-11" name = "__codelineno-13-11" href = "#__codelineno-13-11" > < / a >
< a id = "__codelineno-13-12" name = "__codelineno-13-12" href = "#__codelineno-13-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-13-13" name = "__codelineno-13-13" href = "#__codelineno-13-13" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-14" name = "__codelineno-13-14" href = "#__codelineno-13-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-15" name = "__codelineno-13-15" href = "#__codelineno-13-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-13-16" name = "__codelineno-13-16" href = "#__codelineno-13-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-13-17" name = "__codelineno-13-17" href = "#__codelineno-13-17" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-13-18" name = "__codelineno-13-18" href = "#__codelineno-13-18" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-19" name = "__codelineno-13-19" href = "#__codelineno-13-19" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-20" name = "__codelineno-13-20" href = "#__codelineno-13-20" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-21" name = "__codelineno-13-21" href = "#__codelineno-13-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-13-22" name = "__codelineno-13-22" href = "#__codelineno-13-22" > < / a >
< a id = "__codelineno-13-23" name = "__codelineno-13-23" href = "#__codelineno-13-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-13-24" name = "__codelineno-13-24" href = "#__codelineno-13-24" > < / a > < span class = "kd" > func< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "nx" > TreeNode< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-25" name = "__codelineno-13-25" href = "#__codelineno-13-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > nil< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-13-26" name = "__codelineno-13-26" href = "#__codelineno-13-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span >
< a id = "__codelineno-13-27" name = "__codelineno-13-27" href = "#__codelineno-13-27" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-13-28" name = "__codelineno-13-28" href = "#__codelineno-13-28" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-13-29" name = "__codelineno-13-29" href = "#__codelineno-13-29" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-30" name = "__codelineno-13-30" href = "#__codelineno-13-30" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-31" name = "__codelineno-13-31" href = "#__codelineno-13-31" > < / a > < span class = "w" > < / span > < span class = "nx" > nums< / span > < span class = "w" > < / span > < span class = "p" > =< / span > < span class = "w" > < / span > < span class = "nb" > append< / span > < span class = "p" > (< / span > < span class = "nx" > nums< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "nx" > node< / span > < span class = "p" > .< / span > < span class = "nx" > Val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-13-32" name = "__codelineno-13-32" href = "#__codelineno-13-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.js< / span > < pre > < span > < / span > < code > < a id = "__codelineno-14-1" name = "__codelineno-14-1" href = "#__codelineno-14-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-14-2" name = "__codelineno-14-2" href = "#__codelineno-14-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-14-3" name = "__codelineno-14-3" href = "#__codelineno-14-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-14-4" name = "__codelineno-14-4" href = "#__codelineno-14-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-14-5" name = "__codelineno-14-5" href = "#__codelineno-14-5" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-6" name = "__codelineno-14-6" href = "#__codelineno-14-6" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-7" name = "__codelineno-14-7" href = "#__codelineno-14-7" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-8" name = "__codelineno-14-8" href = "#__codelineno-14-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-14-9" name = "__codelineno-14-9" href = "#__codelineno-14-9" > < / a >
< a id = "__codelineno-14-10" name = "__codelineno-14-10" href = "#__codelineno-14-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-14-11" name = "__codelineno-14-11" href = "#__codelineno-14-11" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-14-12" name = "__codelineno-14-12" href = "#__codelineno-14-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-14-13" name = "__codelineno-14-13" href = "#__codelineno-14-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-14-14" name = "__codelineno-14-14" href = "#__codelineno-14-14" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-15" name = "__codelineno-14-15" href = "#__codelineno-14-15" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-16" name = "__codelineno-14-16" href = "#__codelineno-14-16" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-17" name = "__codelineno-14-17" href = "#__codelineno-14-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-14-18" name = "__codelineno-14-18" href = "#__codelineno-14-18" > < / a >
< a id = "__codelineno-14-19" name = "__codelineno-14-19" href = "#__codelineno-14-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-14-20" name = "__codelineno-14-20" href = "#__codelineno-14-20" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-14-21" name = "__codelineno-14-21" href = "#__codelineno-14-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-14-22" name = "__codelineno-14-22" href = "#__codelineno-14-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-14-23" name = "__codelineno-14-23" href = "#__codelineno-14-23" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-24" name = "__codelineno-14-24" href = "#__codelineno-14-24" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-25" name = "__codelineno-14-25" href = "#__codelineno-14-25" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-14-26" name = "__codelineno-14-26" href = "#__codelineno-14-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.ts< / span > < pre > < span > < / span > < code > < a id = "__codelineno-15-1" name = "__codelineno-15-1" href = "#__codelineno-15-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-15-2" name = "__codelineno-15-2" href = "#__codelineno-15-2" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-3" name = "__codelineno-15-3" href = "#__codelineno-15-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-4" name = "__codelineno-15-4" href = "#__codelineno-15-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-5" name = "__codelineno-15-5" href = "#__codelineno-15-5" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-15-6" name = "__codelineno-15-6" href = "#__codelineno-15-6" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-15-7" name = "__codelineno-15-7" href = "#__codelineno-15-7" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-8" name = "__codelineno-15-8" href = "#__codelineno-15-8" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-9" name = "__codelineno-15-9" href = "#__codelineno-15-9" > < / a > < span class = "w" > < / span > < span class = "nx" > preOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-10" name = "__codelineno-15-10" href = "#__codelineno-15-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-15-11" name = "__codelineno-15-11" href = "#__codelineno-15-11" > < / a >
< a id = "__codelineno-15-12" name = "__codelineno-15-12" href = "#__codelineno-15-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-15-13" name = "__codelineno-15-13" href = "#__codelineno-15-13" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-14" name = "__codelineno-15-14" href = "#__codelineno-15-14" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-15" name = "__codelineno-15-15" href = "#__codelineno-15-15" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-16" name = "__codelineno-15-16" href = "#__codelineno-15-16" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-15-17" name = "__codelineno-15-17" href = "#__codelineno-15-17" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-15-18" name = "__codelineno-15-18" href = "#__codelineno-15-18" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-19" name = "__codelineno-15-19" href = "#__codelineno-15-19" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-20" name = "__codelineno-15-20" href = "#__codelineno-15-20" > < / a > < span class = "w" > < / span > < span class = "nx" > inOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-21" name = "__codelineno-15-21" href = "#__codelineno-15-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-15-22" name = "__codelineno-15-22" href = "#__codelineno-15-22" > < / a >
< a id = "__codelineno-15-23" name = "__codelineno-15-23" href = "#__codelineno-15-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-15-24" name = "__codelineno-15-24" href = "#__codelineno-15-24" > < / a > < span class = "kd" > function< / span > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > |< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "ow" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-25" name = "__codelineno-15-25" href = "#__codelineno-15-25" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "w" > < / span > < span class = "o" > ===< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-15-26" name = "__codelineno-15-26" href = "#__codelineno-15-26" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-15-27" name = "__codelineno-15-27" href = "#__codelineno-15-27" > < / a > < span class = "w" > < / span > < span class = "p" > }< / span >
< a id = "__codelineno-15-28" name = "__codelineno-15-28" href = "#__codelineno-15-28" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-15-29" name = "__codelineno-15-29" href = "#__codelineno-15-29" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-30" name = "__codelineno-15-30" href = "#__codelineno-15-30" > < / a > < span class = "w" > < / span > < span class = "nx" > postOrder< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-31" name = "__codelineno-15-31" href = "#__codelineno-15-31" > < / a > < span class = "w" > < / span > < span class = "nx" > list< / span > < span class = "p" > .< / span > < span class = "nx" > push< / span > < span class = "p" > (< / span > < span class = "nx" > root< / span > < span class = "p" > .< / span > < span class = "nx" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-15-32" name = "__codelineno-15-32" href = "#__codelineno-15-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.c< / span > < pre > < span > < / span > < code > < a id = "__codelineno-16-1" name = "__codelineno-16-1" href = "#__codelineno-16-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-16-2" name = "__codelineno-16-2" href = "#__codelineno-16-2" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-3" name = "__codelineno-16-3" href = "#__codelineno-16-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-4" name = "__codelineno-16-4" href = "#__codelineno-16-4" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-5" name = "__codelineno-16-5" href = "#__codelineno-16-5" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-16-6" name = "__codelineno-16-6" href = "#__codelineno-16-6" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-7" name = "__codelineno-16-7" href = "#__codelineno-16-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-8" name = "__codelineno-16-8" href = "#__codelineno-16-8" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-9" name = "__codelineno-16-9" href = "#__codelineno-16-9" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-16-10" name = "__codelineno-16-10" href = "#__codelineno-16-10" > < / a >
< a id = "__codelineno-16-11" name = "__codelineno-16-11" href = "#__codelineno-16-11" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-16-12" name = "__codelineno-16-12" href = "#__codelineno-16-12" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-13" name = "__codelineno-16-13" href = "#__codelineno-16-13" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-14" name = "__codelineno-16-14" href = "#__codelineno-16-14" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-15" name = "__codelineno-16-15" href = "#__codelineno-16-15" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-16-16" name = "__codelineno-16-16" href = "#__codelineno-16-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-17" name = "__codelineno-16-17" href = "#__codelineno-16-17" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-18" name = "__codelineno-16-18" href = "#__codelineno-16-18" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-19" name = "__codelineno-16-19" href = "#__codelineno-16-19" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-16-20" name = "__codelineno-16-20" href = "#__codelineno-16-20" > < / a >
< a id = "__codelineno-16-21" name = "__codelineno-16-21" href = "#__codelineno-16-21" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-16-22" name = "__codelineno-16-22" href = "#__codelineno-16-22" > < / a > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > root< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "kt" > int< / span > < span class = "w" > < / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-16-23" name = "__codelineno-16-23" href = "#__codelineno-16-23" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "nb" > NULL< / span > < span class = "p" > )< / span >
< a id = "__codelineno-16-24" name = "__codelineno-16-24" href = "#__codelineno-16-24" > < / a > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-25" name = "__codelineno-16-25" href = "#__codelineno-16-25" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-16-26" name = "__codelineno-16-26" href = "#__codelineno-16-26" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > left< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-27" name = "__codelineno-16-27" href = "#__codelineno-16-27" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > right< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > size< / span > < span class = "p" > );< / span >
< a id = "__codelineno-16-28" name = "__codelineno-16-28" href = "#__codelineno-16-28" > < / a > < span class = "w" > < / span > < span class = "n" > arr< / span > < span class = "p" > [(< / span > < span class = "o" > *< / span > < span class = "n" > size< / span > < span class = "p" > )< / span > < span class = "o" > ++< / span > < span class = "p" > ]< / span > < span class = "w" > < / span > < span class = "o" > =< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > -> < / span > < span class = "n" > val< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-16-29" name = "__codelineno-16-29" href = "#__codelineno-16-29" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.cs< / span > < pre > < span > < / span > < code > < a id = "__codelineno-17-1" name = "__codelineno-17-1" href = "#__codelineno-17-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-17-2" name = "__codelineno-17-2" href = "#__codelineno-17-2" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-3" name = "__codelineno-17-3" href = "#__codelineno-17-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-4" name = "__codelineno-17-4" href = "#__codelineno-17-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-17-5" name = "__codelineno-17-5" href = "#__codelineno-17-5" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-6" name = "__codelineno-17-6" href = "#__codelineno-17-6" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-7" name = "__codelineno-17-7" href = "#__codelineno-17-7" > < / a > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-8" name = "__codelineno-17-8" href = "#__codelineno-17-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-17-9" name = "__codelineno-17-9" href = "#__codelineno-17-9" > < / a >
< a id = "__codelineno-17-10" name = "__codelineno-17-10" href = "#__codelineno-17-10" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-17-11" name = "__codelineno-17-11" href = "#__codelineno-17-11" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-12" name = "__codelineno-17-12" href = "#__codelineno-17-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-13" name = "__codelineno-17-13" href = "#__codelineno-17-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-17-14" name = "__codelineno-17-14" href = "#__codelineno-17-14" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-15" name = "__codelineno-17-15" href = "#__codelineno-17-15" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-16" name = "__codelineno-17-16" href = "#__codelineno-17-16" > < / a > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-17" name = "__codelineno-17-17" href = "#__codelineno-17-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-17-18" name = "__codelineno-17-18" href = "#__codelineno-17-18" > < / a >
< a id = "__codelineno-17-19" name = "__codelineno-17-19" href = "#__codelineno-17-19" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-17-20" name = "__codelineno-17-20" href = "#__codelineno-17-20" > < / a > < span class = "k" > void< / span > < span class = "w" > < / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > TreeNode< / span > < span class = "o" > ?< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-17-21" name = "__codelineno-17-21" href = "#__codelineno-17-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "k" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-17-22" name = "__codelineno-17-22" href = "#__codelineno-17-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-17-23" name = "__codelineno-17-23" href = "#__codelineno-17-23" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-24" name = "__codelineno-17-24" href = "#__codelineno-17-24" > < / a > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-25" name = "__codelineno-17-25" href = "#__codelineno-17-25" > < / a > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > Add< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-17-26" name = "__codelineno-17-26" href = "#__codelineno-17-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.swift< / span > < pre > < span > < / span > < code > < a id = "__codelineno-18-1" name = "__codelineno-18-1" href = "#__codelineno-18-1" > < / a > < span class = "cm" > /* 前序遍历 */< / span >
< a id = "__codelineno-18-2" name = "__codelineno-18-2" href = "#__codelineno-18-2" > < / a > < span class = "kd" > func< / span > < span class = "nf" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-3" name = "__codelineno-18-3" href = "#__codelineno-18-3" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-4" name = "__codelineno-18-4" href = "#__codelineno-18-4" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-18-5" name = "__codelineno-18-5" href = "#__codelineno-18-5" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-6" name = "__codelineno-18-6" href = "#__codelineno-18-6" > < / a > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-18-7" name = "__codelineno-18-7" href = "#__codelineno-18-7" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-8" name = "__codelineno-18-8" href = "#__codelineno-18-8" > < / a > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-9" name = "__codelineno-18-9" href = "#__codelineno-18-9" > < / a > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-10" name = "__codelineno-18-10" href = "#__codelineno-18-10" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-11" name = "__codelineno-18-11" href = "#__codelineno-18-11" > < / a >
< a id = "__codelineno-18-12" name = "__codelineno-18-12" href = "#__codelineno-18-12" > < / a > < span class = "cm" > /* 中序遍历 */< / span >
< a id = "__codelineno-18-13" name = "__codelineno-18-13" href = "#__codelineno-18-13" > < / a > < span class = "kd" > func< / span > < span class = "nf" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-14" name = "__codelineno-18-14" href = "#__codelineno-18-14" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-15" name = "__codelineno-18-15" href = "#__codelineno-18-15" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-18-16" name = "__codelineno-18-16" href = "#__codelineno-18-16" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-17" name = "__codelineno-18-17" href = "#__codelineno-18-17" > < / a > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-18-18" name = "__codelineno-18-18" href = "#__codelineno-18-18" > < / a > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-19" name = "__codelineno-18-19" href = "#__codelineno-18-19" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-20" name = "__codelineno-18-20" href = "#__codelineno-18-20" > < / a > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-21" name = "__codelineno-18-21" href = "#__codelineno-18-21" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-22" name = "__codelineno-18-22" href = "#__codelineno-18-22" > < / a >
< a id = "__codelineno-18-23" name = "__codelineno-18-23" href = "#__codelineno-18-23" > < / a > < span class = "cm" > /* 后序遍历 */< / span >
< a id = "__codelineno-18-24" name = "__codelineno-18-24" href = "#__codelineno-18-24" > < / a > < span class = "kd" > func< / span > < span class = "nf" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > TreeNode< / span > < span class = "p" > ?)< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-25" name = "__codelineno-18-25" href = "#__codelineno-18-25" > < / a > < span class = "k" > guard< / span > < span class = "kd" > let< / span > < span class = "nv" > root< / span > < span class = "p" > =< / span > < span class = "n" > root< / span > < span class = "k" > else< / span > < span class = "p" > {< / span >
< a id = "__codelineno-18-26" name = "__codelineno-18-26" href = "#__codelineno-18-26" > < / a > < span class = "k" > return< / span >
< a id = "__codelineno-18-27" name = "__codelineno-18-27" href = "#__codelineno-18-27" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-18-28" name = "__codelineno-18-28" href = "#__codelineno-18-28" > < / a > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-18-29" name = "__codelineno-18-29" href = "#__codelineno-18-29" > < / a > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > left< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-30" name = "__codelineno-18-30" href = "#__codelineno-18-30" > < / a > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > :< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "kr" > right< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-31" name = "__codelineno-18-31" href = "#__codelineno-18-31" > < / a > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > )< / span >
< a id = "__codelineno-18-32" name = "__codelineno-18-32" href = "#__codelineno-18-32" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< div class = "tabbed-block" >
< div class = "highlight" > < span class = "filename" > binary_tree_dfs.zig< / span > < pre > < span > < / span > < code > < a id = "__codelineno-19-1" name = "__codelineno-19-1" href = "#__codelineno-19-1" > < / a > < span class = "c1" > // 前序遍历< / span >
< a id = "__codelineno-19-2" name = "__codelineno-19-2" href = "#__codelineno-19-2" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-3" name = "__codelineno-19-3" href = "#__codelineno-19-3" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-19-4" name = "__codelineno-19-4" href = "#__codelineno-19-4" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：根节点 -> 左子树 -> 右子树< / span >
< a id = "__codelineno-19-5" name = "__codelineno-19-5" href = "#__codelineno-19-5" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-6" name = "__codelineno-19-6" href = "#__codelineno-19-6" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-7" name = "__codelineno-19-7" href = "#__codelineno-19-7" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > preOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-8" name = "__codelineno-19-8" href = "#__codelineno-19-8" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-9" name = "__codelineno-19-9" href = "#__codelineno-19-9" > < / a >
< a id = "__codelineno-19-10" name = "__codelineno-19-10" href = "#__codelineno-19-10" > < / a > < span class = "c1" > // 中序遍历< / span >
< a id = "__codelineno-19-11" name = "__codelineno-19-11" href = "#__codelineno-19-11" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-12" name = "__codelineno-19-12" href = "#__codelineno-19-12" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-19-13" name = "__codelineno-19-13" href = "#__codelineno-19-13" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 根节点 -> 右子树< / span >
< a id = "__codelineno-19-14" name = "__codelineno-19-14" href = "#__codelineno-19-14" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-15" name = "__codelineno-19-15" href = "#__codelineno-19-15" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-16" name = "__codelineno-19-16" href = "#__codelineno-19-16" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > inOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-17" name = "__codelineno-19-17" href = "#__codelineno-19-17" > < / a > < span class = "p" > }< / span >
< a id = "__codelineno-19-18" name = "__codelineno-19-18" href = "#__codelineno-19-18" > < / a >
< a id = "__codelineno-19-19" name = "__codelineno-19-19" href = "#__codelineno-19-19" > < / a > < span class = "c1" > // 后序遍历< / span >
< a id = "__codelineno-19-20" name = "__codelineno-19-20" href = "#__codelineno-19-20" > < / a > < span class = "k" > fn< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "kr" > comptime< / span > < span class = "w" > < / span > < span class = "n" > T< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "kt" > type< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "o" > :< / span > < span class = "w" > < / span > < span class = "o" > ?*< / span > < span class = "n" > inc< / span > < span class = "p" > .< / span > < span class = "n" > TreeNode< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ))< / span > < span class = "w" > < / span > < span class = "o" > !< / span > < span class = "kt" > void< / span > < span class = "w" > < / span > < span class = "p" > {< / span >
< a id = "__codelineno-19-21" name = "__codelineno-19-21" href = "#__codelineno-19-21" > < / a > < span class = "w" > < / span > < span class = "k" > if< / span > < span class = "w" > < / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "w" > < / span > < span class = "o" > ==< / span > < span class = "w" > < / span > < span class = "kc" > null< / span > < span class = "p" > )< / span > < span class = "w" > < / span > < span class = "k" > return< / span > < span class = "p" > ;< / span >
< a id = "__codelineno-19-22" name = "__codelineno-19-22" href = "#__codelineno-19-22" > < / a > < span class = "w" > < / span > < span class = "c1" > // 访问优先级：左子树 -> 右子树 -> 根节点< / span >
< a id = "__codelineno-19-23" name = "__codelineno-19-23" href = "#__codelineno-19-23" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > left< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-24" name = "__codelineno-19-24" href = "#__codelineno-19-24" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > postOrder< / span > < span class = "p" > (< / span > < span class = "n" > T< / span > < span class = "p" > ,< / span > < span class = "w" > < / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > right< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-25" name = "__codelineno-19-25" href = "#__codelineno-19-25" > < / a > < span class = "w" > < / span > < span class = "k" > try< / span > < span class = "w" > < / span > < span class = "n" > list< / span > < span class = "p" > .< / span > < span class = "n" > append< / span > < span class = "p" > (< / span > < span class = "n" > root< / span > < span class = "p" > .< / span > < span class = "o" > ?< / span > < span class = "p" > .< / span > < span class = "n" > val< / span > < span class = "p" > );< / span >
< a id = "__codelineno-19-26" name = "__codelineno-19-26" href = "#__codelineno-19-26" > < / a > < span class = "p" > }< / span >
< / code > < / pre > < / div >
< / div >
< / div >
< / div >
< div class = "admonition note" >
< p class = "admonition-title" > Note< / p >
< p > 我们也可以仅基于循环实现前、中、后序遍历，有兴趣的同学可以自行实现。< / p >
< / div >
< p > 递归过程可分为“递”和“归”两个相反的部分。“递”表示开启新方法，程序在此过程中访问下一个节点；“归”表示函数返回，代表该节点已经访问完毕。如下图所示，为前序遍历二叉树的递归过程。< / p >
< div class = "tabbed-set tabbed-alternate" data-tabs = "3:11" > < input checked = "checked" id = "__tabbed_3_1" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_2" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_3" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_4" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_5" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_6" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_7" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_8" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_9" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_10" name = "__tabbed_3" type = "radio" / > < input id = "__tabbed_3_11" name = "__tabbed_3" type = "radio" / > < div class = "tabbed-labels" > < label for = "__tabbed_3_1" > < 1> < / label > < label for = "__tabbed_3_2" > < 2> < / label > < label for = "__tabbed_3_3" > < 3> < / label > < label for = "__tabbed_3_4" > < 4> < / label > < label for = "__tabbed_3_5" > < 5> < / label > < label for = "__tabbed_3_6" > < 6> < / label > < label for = "__tabbed_3_7" > < 7> < / label > < label for = "__tabbed_3_8" > < 8> < / label > < label for = "__tabbed_3_9" > < 9> < / label > < label for = "__tabbed_3_10" > < 10> < / label > < label for = "__tabbed_3_11" > < 11> < / label > < / div >
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< p > < img alt = "前序遍历的递归过程" src = "../binary_tree_traversal.assets/preorder_step1.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step2" src = "../binary_tree_traversal.assets/preorder_step2.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step3" src = "../binary_tree_traversal.assets/preorder_step3.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step4" src = "../binary_tree_traversal.assets/preorder_step4.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step5" src = "../binary_tree_traversal.assets/preorder_step5.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step6" src = "../binary_tree_traversal.assets/preorder_step6.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step7" src = "../binary_tree_traversal.assets/preorder_step7.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step8" src = "../binary_tree_traversal.assets/preorder_step8.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step9" src = "../binary_tree_traversal.assets/preorder_step9.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step10" src = "../binary_tree_traversal.assets/preorder_step10.png" / > < / p >
< / div >
< div class = "tabbed-block" >
< p > < img alt = "preorder_step11" src = "../binary_tree_traversal.assets/preorder_step11.png" / > < / p >
< / div >
< / div >
< / div >
< h3 id = "_4" > 复杂度分析< a class = "headerlink" href = "#_4" title = "Permanent link" > ¶ < / a > < / h3 >
< p > < strong > 时间复杂度< / strong > ：所有节点被访问一次，使用 < span class = "arithmatex" > \(O(n)\)< / span > 时间，其中 < span class = "arithmatex" > \(n\)< / span > 为节点数量。< / p >
< p > < strong > 空间复杂度< / strong > ：在最差情况下，即树退化为链表时，递归深度达到 < span class = "arithmatex" > \(n\)< / span > ，系统占用 < span class = "arithmatex" > \(O(n)\)< / span > 栈帧空间。< / p >
< h2 id = "__comments" > 评论< / h2 >
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