leetcode 100. The same tree

Given two binary trees, write a function to check if they are the same.

Two trees are considered identical if they are structurally identical and the nodes have identical values.

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

 1 /**
 2  * Definition for a binary tree node.
 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(q == NULL && p == NULL) return true;
14         if(q != NULL && p!= NULL){
15             if(q->val != p->val) return false;
16             else return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
17         } else return false;
18     }
19 };