BZOJ 2301: [HAOI2011]Problem b【莫比乌斯反演

裸懵逼乌斯反演，稍微再容斥一下

#include<bits/stdc++.h>#define MAXN 50001using namespace std;int n,a,b,c,d,k;int mu[MAXN],sum[MAXN];int p[MAXN],tag[MAXN];void init(){mu[1]=sum[1]=1;for(int i=2;i<MAXN;++i){if(!tag[i])p[++p[0]]=i,mu[i]=-1;for(int j=1;j<=p[0];++j){int to=i*p[j];if(to>=MAXN)break;tag[to]=1,mu[to]=-mu[i];if(!(i%p[j])){mu[to]=0;break;}}sum[i]=sum[i-1]+mu[i];}}long long calc(int x,int y){if(x>y)swap(x,y);long long ans=0;for(int L=1,R=0;L<=x;L=R+1){R=min(x/(x/L),y/(y/L));ans+=1ll*(sum[R]-sum[L-1])*(x/L)*(y/L);}return ans;}int main(){init();scanf("%d",&n);while(n--){scanf("%d%d%d%d%d",&a,&b,&c,&d,&k);printf("%lld\n",calc((a-1)/k,(c-1)/k)+calc(b/k,d/k)-calc((a-1)/k,d/k)-calc(b/k,(c-1)/k));}return 0;}