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 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);
     }
 };

递归。