摘要：题面 链接： "CF548E" Description Mike is a bartender at Rico's bar. At Rico's, they put beer glasses in a special shelf. There are n kinds of beer at Rico' 阅读全文

摘要：题面 求$\sum_{i=1}^n\sum_{j=1}^md(ij)$ $\leq 50000$组数据，$1\leq n,m\leq 50000$。 题目分析 首先，你需要知道一个结论： $$ d(ij)=\sum\limits_{x|i}\sum\limits_{y|j}[gcd(x,y)==1] 阅读全文