LeetCode 236. 二叉树的最近公共祖先

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     struct TreeNode *left;
 6  *     struct TreeNode *right;
 7  * };
 8  */
 9 struct TreeNode* lowestCommonAncestor(struct TreeNode* root, struct TreeNode* p, struct TreeNode* q) {
10         if(root==p||root==q||!root)return root;
11         struct TreeNode* left=lowestCommonAncestor(root->left, p, q);
12         struct TreeNode* right=lowestCommonAncestor(root->right, p, q);
13         if(!left&&!right) return NULL;
14         else if(left&&!right) return left;
15         else if(right&&!left) return right; 
16         return root;
17 }