剑指offer 二叉搜索树的第k个结点

 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     int count = 0;
14     TreeNode* KthNode(TreeNode* pRoot, int k) {
15         if(pRoot != NULL) {
16             TreeNode* temp = KthNode(pRoot->left,k);
17             if(temp != NULL)
18                 return temp;
19             count ++;
20             if(count == k)
21                 return pRoot;
22             temp = KthNode(pRoot->right,k);
23             if(temp != NULL)
24                 return temp;
25         }
26         return NULL;
27     }
28 };