# 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 values.


题目翻译:
给两棵树,写一个函数来判断这两棵树是否相同. 我们判定一棵树是否相同的条件为这两棵树的结构相同,并且每个节点的值相同.


解题思路:
这道题中规中矩,很简单,我们直接用DFS前序遍历这两棵树就可以了.

时间复杂度分析:
因为是DFS, 所以时间复杂度为O(n)


代码如下:
```c++
/**
* 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 == NULL && q == NULL)
return true;
else if(p == NULL || q == NULL)
return false;
if(p->val == q->val)
{
bool left = isSameTree(p->left, q->left);
bool right = isSameTree(p->right,q->right);
return left&&right;
}
return false;
}
};

```