soj#552 449E Jzzhu and Squares

分析

https://www.cnblogs.com/Memory-of-winter/p/11209128.html

代码

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e6+;
const int mod = 1e9+;
int phi[N+],is[N+],a[N+],b[N+],c[N+],n,m,t;
signed main(){
    int i,j,k,x=,y=;
    for(i=;i<=N;i++)phi[i]=i;
    for(i=;i<=N;i++)
      if(!is[i])for(j=i;j<=N;j+=i)
       is[j]=,phi[j]=phi[j]/i*(i-);
    for(i=;i<=N;i++){
      x=(x+*i+)%mod;
      y=(y+*i*i)%mod;
      a[i]=((i*i%mod*i%mod-x*i%mod+y)%mod+mod)%mod;
    }
    for(i=;i<=N;i++)
      for(j=i;j<=N;j+=i)
        a[j]=(a[j]+2ll*i*phi[j/i]%mod)%mod;
    for(i=;i<=N;i++){
      b[i]=(b[i-]+a[i]*i%mod)%mod;
      c[i]=(c[i-]+a[i]*i%mod*i%mod)%mod;
      a[i]=(a[i]+a[i-])%mod;
    }
    scanf("%lld",&t);
    while(t--){
      scanf("%lld%lld",&n,&m);
      n++,m++;
      int x=min(n,m);
      printf("%lld\n",((n*m%mod*a[x]%mod-(n+m)*b[x]%mod+c[x])%mod+mod)%mod);
    }
    return ;
}