LeetCode--Same Tree

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.
代码:

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/

bool isSameTree(TreeNode* p, TreeNode* q) {
if(p == NULL && q == NULL)
{
return true;
}
else if(p == NULL && q != NULL)
{
return false;
}
else if( p != NULL && q == NULL)
{
return false;
}
else
{
if(p->val == q->val)
{
return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
}
else
return false;
}
}