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-9;
inline int sgn(DB x){if(abs(x)<EPS)return 0;return(x>0)?1:-1;}
const DB Pi=acos(-1.0);

inline int gint()
  {
        int res=0;bool neg=0;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return 0;
        if(z=='-'){neg=1;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar());
        return (neg)?-res:res; 
    }
inline LL gll()
  {
      LL res=0;bool neg=0;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return 0;
        if(z=='-'){neg=1;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar());
        return (neg)?-res:res;   
  }

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

LL N,M;
LL ans;

LL mu[maxN+100],sum[maxN+100];
LL prime[maxN+100],tol;
bool isnotprime[maxN+100];
inline void prepare()
  {
      LL i,j;
      mu[1]=1;
      re(i,2,N)
        {
            if(!isnotprime[i]){mu[i]=-1;prime[++tol]=i;}
            for(j=1;j<=tol && prime[j]*i<=N;j++)
              {
                  isnotprime[prime[j]*i]=1;
                  if(i%prime[j]==0){mu[prime[j]*i]=0;break;}
                  mu[prime[j]*i]=-mu[i];
              }
        }
      re(i,1,N) sum[i]=(sum[i-1]+(mu[i]*i*i)%Mod)%Mod;
  }

inline LL F(LL x,LL y)
  {
      LL res=0,e,last;
      for(e=1;e<=x;e=last+1)
        {
            last=min(x/(x/e),y/(y/e));
            upmin(last,x);
            LL s=(sum[last]-sum[e-1])%Mod;
            LL t=((1+(x/e))*(x/e)/2%Mod)*((1+(y/e))*(y/e)/2%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=0;
      LL d,last;
      for(d=1;d<=N;d=last+1)
        {
            last=min(N/(N/d),M/(M/d));
            upmin(last,N);
            LL s=(d+last)*(last-d+1)/2%Mod;
                LL t=F(N/d,M/d);
            ans=(ans+s*t%Mod)%Mod;
        }
      ans=(ans%Mod+Mod)%Mod;
      cout<<ans<<endl;
      return 0;
  }

#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-9;
inline int sgn(DB x){if(abs(x)<EPS)return 0;return(x>0)?1:-1;}
const DB Pi=acos(-1.0);

inline int gint()
  {
        int res=0;bool neg=0;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return 0;
        if(z=='-'){neg=1;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar());
        return (neg)?-res:res; 
    }
inline LL gll()
  {
      LL res=0;bool neg=0;char z;
        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());
        if(z==EOF)return 0;
        if(z=='-'){neg=1;z=getchar();}
        for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar());
        return (neg)?-res:res; 
    }

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

LL N,M;

LL f[maxN+100];
LL prime[maxN+100],tol;
bool isnotprime[maxN+100];

inline void prepare()
  {
      f[1]=1;
      LL i,j;
      re(i,2,N)
        {
            if(!isnotprime[i]){prime[++tol]=i;f[i]=1-i;}
            for(j=1;j<=tol && i*prime[j]<=N;j++)
              {
                  isnotprime[i*prime[j]]=1;
                  if(i%prime[j]==0)
                          {
                              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=0;
        re(i,1,N)
          {
              LL res=i;
              res=res*((1+(N/i))*(N/i)/2%Mod)%Mod;
              res=res*((1+(M/i))*(M/i)/2%Mod)%Mod;
              res=res*f[i]%Mod;
              ans=(ans+res)%Mod;
          }
        ans=(ans%Mod+Mod)%Mod;
        cout<<ans<<endl;
        return 0;
    }

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