/**
* 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:
TreeNode* inorderSuccessor(TreeNode* root, TreeNode* p) {
TreeNode* ret;
if(!root) return root;
if(root->val>p->val){
TreeNode * left = inorderSuccessor(root->left,p);
ret=left?left:root;
}else{
ret=inorderSuccessor(root->right,p);
}
return ret;
}
};