剑指 Offer 54. 二叉搜索树的第k大节点

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int ans;
    int n = 0;
    int kthLargest(TreeNode* root, int k) {
        myKthLargest(root, k);
        return ans;
    }
    void myKthLargest(TreeNode *T, int k){
        if (T == NULL){
            return;
        }   
        myKthLargest(T->right, k);
        n++;
        if(n == k){
            ans = T->val;
            return;
        }
        myKthLargest(T->left, k);
        
    }
};