[leetcode] 11. Same Tree

因为我刷题是难度不是按发布日期，所以就有可能遇到这种情况，比如这个。。。

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.

这道题跟之前那道是递进的，而且这道在前，先用它学会怎么判断二叉树相等，然后再去做那道镜像判断。但是呢，我是先把镜像撸出来了，所以这道题就是把之前的题解里面那个子函数拉出来就行。

题解如下：

/**
 * 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 == NULL && q == NULL)
	{
		return true;
	}

	if (p == NULL || q == NULL)
	{
		return false;
	}

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

就是这样。