Same Tree

来源：Leetcode

原帖：http://oj.leetcode.com/problems/same-tree/

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.

代码：

 /**  
  * Definition for binary tree  
  * 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) return true;  
     if (p && !q || !p && q) return false;  
     if (p->val != q->val) return false;  
     return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);  
   }  
 };