【二叉树 - LeetCode】236. 二叉树的最近公共祖先

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