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39 lines
1.0 KiB
39 lines
1.0 KiB
8 months ago
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/**
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* File: binary_tree_bfs.dart
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* Created Time: 2023-04-03
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* Author: liuyuxin (gvenusleo@gmai.com)
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*/
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import 'dart:collection';
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import '../utils/print_util.dart';
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import '../utils/tree_node.dart';
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/* 層序走訪 */
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List<int> levelOrder(TreeNode? root) {
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// 初始化佇列，加入根節點
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Queue<TreeNode?> queue = Queue();
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queue.add(root);
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// 初始化一個串列，用於儲存走訪序列
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List<int> res = [];
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while (queue.isNotEmpty) {
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TreeNode? node = queue.removeFirst(); // 隊列出隊
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res.add(node!.val); // 儲存節點值
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if (node.left != null) queue.add(node.left); // 左子節點入列
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if (node.right != null) queue.add(node.right); // 右子節點入列
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}
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return res;
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}
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/* Driver Code */
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void main() {
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/* 初始化二元樹 */
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// 這裡藉助了一個從陣列直接生成二元樹的函式
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TreeNode? root = listToTree([1, 2, 3, 4, 5, 6, 7]);
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print("\n初始化二元樹\n");
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printTree(root);
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// 層序走訪
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List<int> res = levelOrder(root);
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print("\n層序走訪的節點列印序列 = $res");
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}
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