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 50001
using 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;
}