/**
* 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* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
if(root == NULL || root == p || root == q)return root;
TreeNode* l = lowestCommonAncestor(root->left, p, q);
TreeNode* r = lowestCommonAncestor(root->right, p, q);
if(l == NULL)return r;
if(r == NULL)return l;
return root;
}
};