35 lines
811 B
Java
35 lines
811 B
Java
# 54. 二叉查找树的第 K 个结点
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[NowCoder](https://www.nowcoder.com/practice/ef068f602dde4d28aab2b210e859150a?tpId=13&tqId=11215&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
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## 解题思路
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利用二叉查找树中序遍历有序的特点。
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```java
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private TreeNode ret;
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private int cnt = 0;
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public TreeNode KthNode(TreeNode pRoot, int k) {
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inOrder(pRoot, k);
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return ret;
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}
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private void inOrder(TreeNode root, int k) {
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if (root == null || cnt >= k)
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return;
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inOrder(root.left, k);
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cnt++;
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if (cnt == k)
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ret = root;
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inOrder(root.right, k);
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}
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```
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<div align="center"><img width="320px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/githubio/公众号二维码-1.png"></img></div>
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