codeforces 630K - Indivisibility

K. Indivisibility

题意:给一个n(1 <= n <= 10^18)的区间，问区间中有多少个数不能被2~10这些数整除；

整除只需要看素数即可，只有2,3,5,7四个素数；基本的容斥原理；数据很小直接用二进制模拟了；

int main()
{
    ll n,a[] = {,,,};
    scanf("%I64d",&n);
    ll cnt = n;
    for(int id = ;id < (<<);id++){
        int num = ;
        rep0(i,,)if(id &(<<i)){
            num *= a[i];
        }
        int t = ;
        if(__builtin_popcount(id) & ) t = -;
        cnt += 1LL*t*(n/num);
    }
    cout<<cnt;
    return ;
}