[leetcode] 100. Same Tree 解题报告

题目链接：https://leetcode.com/problems/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.

思路：同时遍历一遍树，发现任何一个节点不相等则两棵树不相等。写水题的感觉好爽

代码如下：

/**
 * Definition for a binary tree node.
 * 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;
        if(p->val != q->val)    return false;
        return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
    }
};