LeetCode 100. Same Tree

100. 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.

/** * 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 != NULL && q != NULL)            return p->val == q->val && isSameTree(p->left, q->left) && isSameTree(p->right, q->right);        return p == NULL && q == NULL;    }};