LeetCode OJ

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.

解题思路：

递归求解。先判断根，然后递归判断左子树和右子树

代码

 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         }
16         else if (p != NULL && q != NULL && p->val == q->val ){
17             return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
18         } else {
19             return false;
20         }
21     }
22 };