# BZOJ 4407 于神之怒加强版

http://www.lydsy.com/JudgeOnline/problem.php?id=4407

来自:http://blog.csdn.net/ws_yzy/article/details/50670213

#include<cstdio>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<cstring>
#define ll long long
const ll Mod=1000000007;
ll f[5000005],sum[5000005],p[5000005],s[5000005];
bool mark[5000005];
ll K,n,m;
ll t=0,f=1;char ch=getchar();
while (ch<'0'||'9'<ch){if (ch=='-') f=-1;ch=getchar();}
while ('0'<=ch&&ch<='9'){t=t*10+ch-'0';ch=getchar();}
return t*f;
}
ll Pow(ll x,ll y){
ll res=1;
while (y){
if (y%2) res=(res*x)%Mod;
y/=2;
x=(x*x)%Mod;
}
return res;
}
void init(){
f[1]=1;
for (int i=2;i<=5000000;i++){
if (!mark[i]){
p[++p[0]]=i;
s[p[0]]=Pow(i,K);
f[i]=s[p[0]]-1;
}
for (int j=1;j<=p[0]&&p[j]*i<=5000000;j++){
mark[p[j]*i]=1;
if (i%p[j]==0){
f[i*p[j]]=f[i]*s[j]%Mod;
break;
}
f[i*p[j]]=f[i]*f[p[j]]%Mod;
}
}
for (int i=1;i<=5000000;i++)
sum[i]=sum[i-1]+f[i]%Mod;
}
int main(){
init();
while (T--){
if (n>m) std::swap(n,m);
int j=1;
ll ans=0;
for (int i=1;i<=n;i=j+1){
j=std::min(n/(n/i),m/(m/i));
ans+=(((n/i)*(m/i)%Mod)*(sum[j]-sum[i-1]))%Mod;
ans%=Mod;
}
printf("%lld\n",ans);
}
return 0;
}

posted @ 2016-07-16 16:44  GFY  阅读(455)  评论(0编辑  收藏  举报