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50 lines
1.3 KiB
50 lines
1.3 KiB
/**
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* File: preorder_traversal_iii_compact.cs
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* Created Time: 2023-04-17
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* Author: hpstory (hpstory1024@163.com)
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*/
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namespace hello_algo.chapter_backtracking;
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public class preorder_traversal_iii_compact {
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static List<TreeNode> path;
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static List<List<TreeNode>> res;
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/* 前序遍历：例题三 */
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static void preOrder(TreeNode root) {
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// 剪枝
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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(new List<TreeNode>(path));
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path.RemoveAt(path.Count - 1);
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return;
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}
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preOrder(root.left);
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preOrder(root.right);
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// 回退
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path.RemoveAt(path.Count - 1);
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}
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[Test]
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public void Test() {
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TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
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Console.WriteLine("\n初始化二叉树");
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PrintUtil.PrintTree(root);
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// 前序遍历
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path = new List<TreeNode>();
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res = new List<List<TreeNode>>();
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preOrder(root);
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Console.WriteLine("\n输出所有根节点到节点 7 的路径，路径中不包含值为 3 的节点");
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foreach (List<TreeNode> path in res) {
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PrintUtil.PrintList(path.Select(p => p.val).ToList());
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}
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}
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}
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