LeetCode 236. 二叉树的最近公共祖先

class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
    	if(!root || root == p || root == q)
    		return root;
    	TreeNode *left = lowestCommonAncestor(root->left, p, q);
    	TreeNode *right = lowestCommonAncestor(root->right, p, q);
    	if(!left && !right)//左右都没有找到p，q
    		return NULL;//返回NULL
    	if(left && right)//左右都找到了p,q，root就是答案
    		return root;
    	else//一遍找到了p,q，返回找到的那边
    		return left ? left : right;
    }
};