问题:
[n/k]/d==[n/(kd)];
线性筛正确性证明
这么求逆元Right?a=k*p;
1LL转化作用域
long long做数组下标
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
typedef long long Lint;
const int maxn=1000009;
const int mm=1000000007;
int T;
Lint n,m;
Lint ksm(Lint a,Lint p){
Lint ret=1;
for(;p;p>>=1,a=a*a%mm){
if(p&1)ret=ret*a%mm;
}
return ret;
}
Lint inv(Lint x){
return ksm(x,mm-2);
}
Lint g[maxn];
Lint invg[maxn];
Lint prime[maxn];
int vis[maxn],cnt;
int mu[maxn];
Lint f[maxn];
int Lineshake(){
vis[1]=1;mu[1]=1;
for(int i=2;i<=1000000;++i){
if(!vis[i]){
prime[++cnt]=i;
mu[i]=-1;
}
for(int j=1;(j<=cnt)&&(i*prime[j]<=1000000);++j){
vis[i*prime[j]]=1;
if(i%prime[j]==0){
mu[i*prime[j]]=0;break;
}
mu[i*prime[j]]=-mu[i];
}
}
f[0]=0;f[1]=1;
for(int i=2;i<=1000000;++i)f[i]=(f[i-1]+f[i-2])%mm;
for(int i=0;i<=1000000;++i)g[i]=1;
for(int d=1;d<=1000000;++d){
Lint invf=inv(f[d]);
for(int k=1;k*d<=1000000;++k){
if(mu[k]==1){
g[k*d]=g[k*d]*f[d]%mm;
}
if(mu[k]==-1){
g[k*d]=g[k*d]*invf%mm;
}
}
}
for(int i=1;i<=1000000;++i)g[i]=g[i-1]*g[i]%mm;
for(int i=0;i<=1000000;++i)invg[i]=inv(g[i]);
}
int Init(){
cnt=0;
memset(g,0,sizeof(g));
memset(vis,0,sizeof(vis));
}
int Getans(){
if(n>m)swap(n,m);
Lint ret=1;
Lint last;
for(int i=1;i<=n;i=last+1){
last=min(n/(n/i),m/(m/i));
ret=ret*ksm(g[last]*invg[i-1]%mm,(n/i)*1LL*(m/i))%mm;
}
return (int)ret%mm;
}
int main(){
Init();
Lineshake();
scanf("%d",&T);
while(T--){
scanf("%lld%lld",&n,&m);
printf("%d\n",Getans());
}
return 0;
}