## 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.

### Analysis:

Recursively check the left child and right child.  If the value is different, or if one of the two nodes is null, return false.

### Code(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) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if (!p && !q) {return true;}
if ((!p && q) || (!q && p)){return false;}
if (p->val!=q->val){return false;}
return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
}
};


### Code(Python):

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

class Solution:
# @param p, a tree node
# @param q, a tree node
# @return a boolean
def isSameTree(self, p, q):
if p == None and q == None:
return True
elif p == None and q != None:
return False
elif p != None and q == None:
return False
elif p.val != q.val:
return False
else:
return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)