LeetCode : 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&&!q)
           return true;
         else if(!p&&q)
             return false;
         else if(p&&!q)
             return false;
         else
            {
                if(p->val!=q->val)
                   return false;
                else
                  return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
            }
    }
};