题目描述

blablabla

样例

blablabla

算法1

/**
 * 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) return NULL;
        if (root==p || root==q) return root;
        auto left=lowestCommonAncestor(root->left,p,q);
        auto right=lowestCommonAncestor(root->right,p,q);
        if (left && right) return root;
        if (left) return left;
        return right;

    }
};