leetcode 之 same tree

题目:

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.

解法：

简单的递归

class Solution {

public:

    bool isSameTree(TreeNode* p, TreeNode* q) {

      if(p == NULL && q == NULL)

        return true;

      else if(p == NULL || q == NULL)

        return false;

      else if(p->val != q->val)

        return false;

      bool left = isSameTree(p->left,q->left);

      bool right = isSameTree(p->right,q->right);

      return right && left;

    }

};