leetcode腾讯精选230

题目：https://leetcode-cn.com/problems/kth-smallest-element-in-a-bst/submissions/
代码：
/**

• 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 kthSmallest(TreeNode root, int k) {
  TreeNode *pcur = root;
  if(root ==NULL)
  return -1;
  vector array;
  stack s;
  while(!s.empty()||root)
  {
  while(pcur)
  {
  s.push(pcur);
  pcur = pcur->left;
  }

        if(s.empty())
       {
           break;
       }
   	pcur = s.top();
   	array.push_back(pcur->val);
   	s.pop();
       
      
   	pcur = pcur->right;
  

  }
  return array[k - 1];
  }

};