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48 lines
985 B
48 lines
985 B
/**
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* File: preorder_traversal_iii_compact.dart
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* Created Time: 2023-08-10
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* Author: liuyuxin (gvenusleo@gmail.com)
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*/
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import '../utils/print_util.dart';
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import '../utils/tree_node.dart';
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/* 前序遍历：例题三 */
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void preOrder(
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TreeNode? root,
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List<TreeNode> path,
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List<List<TreeNode>> res,
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) {
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if (root == null || root.val == 3) {
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return;
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}
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// 尝试
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path.add(root);
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if (root.val == 7) {
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// 记录解
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res.add(List.from(path));
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}
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preOrder(root.left, path, res);
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preOrder(root.right, path, res);
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// 回退
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path.removeLast();
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}
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/* Driver Code */
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void main() {
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TreeNode? root = listToTree([1, 7, 3, 4, 5, 6, 7]);
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print("\n初始化二叉树");
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printTree(root);
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// 前序遍历
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List<TreeNode> path = [];
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List<List<TreeNode>> res = [];
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preOrder(root, path, res);
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print("\n输出所有根节点到节点 7 的路径");
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for (List<TreeNode> vals in res) {
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print(List.generate(vals.length, (i) => vals[i].val));
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}
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}
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