摘要：
The set S originally contains numbers from 1 to n. But unfortunately, due to the data error, one of the numbers in the set got duplicated to another n 阅读全文
摘要：
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: Example 2: Approach #1: 阅读全文
摘要：
Given a string representing an expression of fraction addition and subtraction, you need to return the calculation result in string format. The final 阅读全文
摘要：
Given the coordinates of four points in 2D space, return whether the four points could construct a square. The coordinate (x,y) of a point is represen 阅读全文