LeetCode---(100)Same Tree

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.

首先考虑递归的方法：

/** * 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==NULL&&q==NULL)            return true;        else if(p==NULL||q==NULL)            return false;        return p->val==q->val&&isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);    }};