bzoj2154

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<fstream>
#include<algorithm>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<utility>
#include<set>
#include<bitset>
#include<vector>
#include<functional>
#include<deque>
#include<cctype>
#include<climits>
#include<complex>

using namespace std;

typedef long long LL;
typedef double DB;
typedef pair<int,int> PII;
typedef complex<DB> CP;

#define mmst(a,v) memset(a,v,sizeof(a))
#define mmcy(a,b) memcpy(a,b,sizeof(a))
#define re(i,a,b)  for(i=a;i<=b;i++)
#define red(i,a,b) for(i=a;i>=b;i--)
#define fi first
#define se second
#define m_p(a,b) make_pair(a,b)
#define SF scanf
#define PF printf
#define two(k) (1<<(k))

template<class T>inline T sqr(T x){return x*x;}
template<class T>inline void upmin(T &t,T tmp){if(t>tmp)t=tmp;}
template<class T>inline void upmax(T &t,T tmp){if(t<tmp)t=tmp;}

const DB EPS=1e-;
inline int sgn(DB x){if(abs(x)<EPS)return ;return(x>)?:-;}
const DB Pi=acos(-1.0);

inline int gint()
  {
        int res=;bool neg=;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return ;
        if(z=='-'){neg=;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());
        return (neg)?-res:res;
    }
inline LL gll()
  {
      LL res=;bool neg=;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return ;
        if(z=='-'){neg=;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());
        return (neg)?-res:res;
  }

const LL maxN=10000000LL;
const LL Mod=20101009LL;

LL N,M;
LL ans;

LL mu[maxN+],sum[maxN+];
LL prime[maxN+],tol;
bool isnotprime[maxN+];
inline void prepare()
  {
      LL i,j;
      mu[]=;
      re(i,,N)
        {
            if(!isnotprime[i]){mu[i]=-;prime[++tol]=i;}
            for(j=;j<=tol && prime[j]*i<=N;j++)
              {
                  isnotprime[prime[j]*i]=;
                  if(i%prime[j]==){mu[prime[j]*i]=;break;}
                  mu[prime[j]*i]=-mu[i];
              }
        }
      re(i,,N) sum[i]=(sum[i-]+(mu[i]*i*i)%Mod)%Mod;
  }

inline LL F(LL x,LL y)
  {
      LL res=,e,last;
      for(e=;e<=x;e=last+)
        {
            last=min(x/(x/e),y/(y/e));
            upmin(last,x);
            LL s=(sum[last]-sum[e-])%Mod;
            LL t=((+(x/e))*(x/e)/%Mod)*((+(y/e))*(y/e)/%Mod)%Mod;//记住要多加括号
            res=(res+s*t%Mod)%Mod;
        }
      return res;
  }

int main()
  {
      freopen("bzoj2154.in","r",stdin);
      freopen("bzoj2154.out","w",stdout);
      N=gll();M=gll();
      if(N>M)swap(N,M);
        prepare();
      ans=;
      LL d,last;
      for(d=;d<=N;d=last+)
        {
            last=min(N/(N/d),M/(M/d));
            upmin(last,N);
            LL s=(d+last)*(last-d+)/%Mod;
                LL t=F(N/d,M/d);
            ans=(ans+s*t%Mod)%Mod;
        }
      ans=(ans%Mod+Mod)%Mod;
      cout<<ans<<endl;
      return ;
  }

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<fstream>
#include<algorithm>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<utility>
#include<set>
#include<bitset>
#include<vector>
#include<functional>
#include<deque>
#include<cctype>
#include<climits>
#include<complex>

using namespace std;

typedef long long LL;
typedef double DB;
typedef pair<int,int> PII;
typedef complex<DB> CP;

#define mmst(a,v) memset(a,v,sizeof(a))
#define mmcy(a,b) memcpy(a,b,sizeof(a))
#define re(i,a,b)  for(i=a;i<=b;i++)
#define red(i,a,b) for(i=a;i>=b;i--)
#define fi first
#define se second
#define m_p(a,b) make_pair(a,b)
#define SF scanf
#define PF printf
#define two(k) (1<<(k))

template<class T>inline T sqr(T x){return x*x;}
template<class T>inline void upmin(T &t,T tmp){if(t>tmp)t=tmp;}
template<class T>inline void upmax(T &t,T tmp){if(t<tmp)t=tmp;}

const DB EPS=1e-;
inline int sgn(DB x){if(abs(x)<EPS)return ;return(x>)?:-;}
const DB Pi=acos(-1.0);

inline int gint()
  {
        int res=;bool neg=;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return ;
        if(z=='-'){neg=;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());
        return (neg)?-res:res;
    }
inline LL gll()
  {
      LL res=;bool neg=;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return ;
        if(z=='-'){neg=;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());
        return (neg)?-res:res;
    }

const LL Mod=20101009LL;
const LL maxN=10000000LL;

LL N,M;

LL f[maxN+];
LL prime[maxN+],tol;
bool isnotprime[maxN+];

inline void prepare()
  {
      f[]=;
      LL i,j;
      re(i,,N)
        {
            if(!isnotprime[i]){prime[++tol]=i;f[i]=-i;}
            for(j=;j<=tol && i*prime[j]<=N;j++)
              {
                  isnotprime[i*prime[j]]=;
                  if(i%prime[j]==)
                          {
                              f[i*prime[j]]=f[i];
                                break;
                            }
                  f[i*prime[j]]=f[i]*f[prime[j]]%Mod;
              }
        }
  }

int main()
  {
      freopen("bzoj2154.in","r",stdin);
        freopen("bzoj2154.out","w",stdout);
        LL i;
        N=gll();M=gll();
        if(N>M)swap(N,M);
        prepare();
        LL ans=;
        re(i,,N)
          {
              LL res=i;
              res=res*((+(N/i))*(N/i)/%Mod)%Mod;
              res=res*((+(M/i))*(M/i)/%Mod)%Mod;
              res=res*f[i]%Mod;
              ans=(ans+res)%Mod;
          }
        ans=(ans%Mod+Mod)%Mod;
        cout<<ans<<endl;
        return ;
    }

来自：http://maijing3007.blog.163.com/blog/static/246120003201545101527359