/**

  * Definition for binary tree

  * 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->val != q->val)

             return false;

         else

             return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);

     }

 };