二叉搜索树第k个节点

 1 /*
 2 struct TreeNode {
 3     int val;
 4     struct TreeNode *left;
 5     struct TreeNode *right;
 6     TreeNode(int x) :
 7             val(x), left(NULL), right(NULL) {
 8     }
 9 };
10 */
11 class Solution {
12 public:
13     TreeNode* KthNode(TreeNode* pRoot, int k)
14     {
15         if(!pRoot) return nullptr;
16         vector<TreeNode*> res;
17         Sortnode(pRoot,res);
18         if(k<=0 || k>res.size()) return nullptr;
19         
20         return res[k-1];
21     }
22     void Sortnode(TreeNode* root,vector<TreeNode*>& vec){
23         if(!root) return;
24         Sortnode(root->left,vec);
25         vec.push_back(root);
26         Sortnode(root->right,vec);
27     }
28 };