题解 | #二叉搜索树的第k个节点#
二叉搜索树的第k个节点
https://www.nowcoder.com/practice/57aa0bab91884a10b5136ca2c087f8ff
import java.util.*; /* * public class TreeNode { * int val = 0; * TreeNode left = null; * TreeNode right = null; * public TreeNode(int val) { * this.val = val; * } * } */ public class Solution { /** * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 * * * @param proot TreeNode类 * @param k int整型 * @return int整型 */ int k, ans = -1; public int KthNode (TreeNode proot, int k) { if(proot == null) return -1; this.k = k; dfs(proot); return ans; } void dfs(TreeNode node) { if(node == null) return ; dfs(node.left); if(k == 0) return ; if(--k == 0) { ans = node.val; return ; } dfs(node.right); } }