给定一棵二叉搜索树,请找出其中第 k 大的节点的值。
示例 1:
输入: root = [3,1,4,null,2], k = 1
3
/ \
1 4
\
2
输出: 4
示例 2:
输入: root = [5,3,6,2,4,null,null,1], k = 3
5
/ \
3 6
/ \
2 4
/
1
输出: 4
限制:
- 1 ≤ k ≤ 二叉搜索树元素个数
/**
* Definition for a binary tree node.
* function TreeNode(val) {
* this.val = val;
* this.left = this.right = null;
* }
*/
/**
* @param {TreeNode} root
* @param {number} k
* @return {number}
*/
var kthLargest = function (root, k) {
let ans = 0,
count = 0;
const helper = (root, k) => {
if (root.right != null) helper(root.right, k);
if (++count == k) {
ans = root.val;
return;
}
if (root.left != null) helper(root.left, k);
};
helper(root, k);
return ans;
};