Eiffel的博客

莫比乌斯函数，它的定义如下：       （1）若，那么     （2）若，均为互异素数，那么     （3）其它情况下 莫比乌斯函数计算模板：#define MAXN 101 bool vis[MAXN]; int primes[MAXN]; int miu[MAXN]; int calc(int limit) { memset(vis,

GCD Given 5 integers: a, b, c, d, k, you're to find x in a...b, y in c...d that GCD(x, y) = k. GCD(x, y) means the greatest common divisor of x and y. Since the number of choices may be very larg

Visible Trees There are many trees forming a m * n grid, the grid starts from (1,1). Farmer Sherlock is standing at (0,0) point. He wonders how many trees he can see.  If two trees and S