Same Tree

一、问题描述

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

二、思路

递归的难点在于退出条件，即两棵树同时为空则相同，否则任何一颗为空都不相同，

三、代码

/**
 * 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:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(!p || !q){
            if(!p && !q) 
                return true;
            return false;
        }
        return (p -> val == q -> val) && isSameTree(p -> left,q -> left) && isSameTree(p -> right,q -> right);
    }
};