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