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.

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

递归。