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.
给定两个二叉树，判断是否完全相同。
若两个二叉树完全相同，则每个节点的左子树和右子树必然都相同。
可以采用递归方式，从根节点开始：
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool isSameTree(TreeNode *p, TreeNode *q) { 13 if(p == NULL && q == NULL) 14 return true; 15 else if(p == NULL || q == NULL) 16 return false; 17 18 if(p->val != q->val) 19 return false; 20 21 bool left = isSameTree(p->left,q->left); 22 bool right = isSameTree(p->right,q->right); 23 24 return left && right; 25 } 26 };
原文：http://www.cnblogs.com/fanchangfa/p/4041635.html