39 lines
1.1 KiB
Dart
39 lines
1.1 KiB
Dart
/**
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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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/* Level-order traversal */
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List<int> levelOrder(TreeNode? root) {
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// Initialize queue, add root node
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Queue<TreeNode?> queue = Queue();
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queue.add(root);
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// Initialize a list to store the traversal sequence
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List<int> res = [];
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while (queue.isNotEmpty) {
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TreeNode? node = queue.removeFirst(); // Queue dequeues
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res.add(node!.val); // Save node value
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if (node.left != null) queue.add(node.left); // Left child node enqueues
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if (node.right != null) queue.add(node.right); // Right child node enqueues
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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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/* Initialize binary tree */
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// Use a specific function to convert an array into a binary tree
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TreeNode? root = listToTree([1, 2, 3, 4, 5, 6, 7]);
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print("\nInitialize binary tree\n");
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printTree(root);
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// Level-order traversal
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List<int> res = levelOrder(root);
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print("\nPrint sequence of nodes in level-order traversal = $res");
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}
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