## 题目描述

Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

``````Input:     1         1
/ \       / \
2   3     2   3

[1,2,3],   [1,2,3]

Output: true``````

Example 2:

``````Input:     1         1
/           \
2             2

[1,2],     [1,null,2]

Output: false``````

Example 3:

``````Input:     1         1
/ \       / \
2   1     1   2

[1,2,1],   [1,1,2]

Output: false``````

## 解法一

### Python

``````# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def isSameTree(self, p, q):
"""
:type p: TreeNode
:type q: TreeNode
:rtype: bool
"""
if (p is None and q is None) \
or (p is not None and q is not None and p.val == q.val
and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)):
return True
return False``````

### Java

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if ((p == null && q == null) ||
(p != null && q != null && p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right))) {
return true;
}
return false;
}
}``````

### C++

``````/**
* Definition for a binary tree node.
* 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 == nullptr && q == nullptr) ||
(p != nullptr && q != nullptr && p->val == q->val && isSameTree(p->left, q->left) &&
isSameTree(p->right, q->right))) {
return true;
}
return false;
}
};``````