描述
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c.
Example 1:
Input: 5
Output: True
Explanation: 1 * 1 + 2 * 2 = 5
Example 2:
Input: 3
Output: False
这道题让我们求一个数是否能由平方数之和组成，刚开始博主没仔细看题，没有看到必须要是两个平方数之和，博主以为任意一个就可以。
