题目：
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.
判断两个二叉树是否相同，如果相同则必须结构相同并且每个节点的值相等
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 == NULL || q == NULL) return p == q; return p->val == q->val && isSameTree(p->left,q->left) && isSameTree(p->right,q->right); } };
原文：http://www.cnblogs.com/zhangbaochong/p/5154238.html