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42 lines
1.1 KiB
42 lines
1.1 KiB
/**
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* File: binary_tree_bfs.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_tree
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import utils.TreeNode
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import utils.printTree
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import java.util.*
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/* 层序遍历 */
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fun levelOrder(root: TreeNode?): MutableList<Int> {
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// 初始化队列，加入根节点
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val queue = LinkedList<TreeNode?>()
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queue.add(root)
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// 初始化一个列表，用于保存遍历序列
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val list = mutableListOf<Int>()
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while (queue.isNotEmpty()) {
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val node = queue.poll() // 队列出队
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list.add(node?._val!!) // 保存节点值
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if (node.left != null)
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queue.offer(node.left) // 左子节点入队
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if (node.right != null)
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queue.offer(node.right) // 右子节点入队
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}
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return list
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}
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/* Driver Code */
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fun main() {
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/* 初始化二叉树 */
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// 这里借助了一个从列表直接生成二叉树的函数
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val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
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println("\n初始化二叉树\n")
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printTree(root)
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/* 层序遍历 */
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val list = levelOrder(root)
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println("\n层序遍历的节点打印序列 = $list")
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} |