摘要：
题目描述 Let's denote a function You are given an array aa consisting of nn integers. You have to calculate the sum of d(a_{i},a_{j})d(ai,aj) over all p 阅读全文
摘要：
Discipntion Let's call an array a of size n coprime iff gcd(a1, a2, ..., an) = 1, where gcd is the greatest common divisor of the arguments. You are g 阅读全文