BZOJ3667: Rabin-Miller算法

应用

但是不知道为什么我的素数测试出错几率很大？

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<ctime>
using namespace std;
#define ll long long
ll n,m;
ll lowbit(ll x){return x&-x;}
const
 int maxn=5000000;
bool check[50000001];
int  prime[50000001];
int tot;
ll factor[101];
int t;
/*
inline ll mult(ll a,ll x,ll mod)
{
    a%=mod,x%=mod;
    ll res=0,base=a,i;
    for(i=1;i<=x;i<<=1,base<<=1,base%=mod)
       if(i&x)res+=base,res%=mod;
    return res;
}*/
#define LL ll
inline LL mult(LL a,LL b,LL p)
{
    a%=p; b%=p;
    LL t=(a*b-(LL)((double)a/p*b+0.5)*p);
    return t<0?t+p:t;
}
 
inline ll pow(ll a,ll x,ll mod)//a^x
{
    ll res=1,base=a,i;
    for(i=1;i<=x;i<<=1,base=mult(base,base,mod))
      if(i&x)res=mult(res,base,mod);
    return res;
}
inline ll gcd(ll a,ll b)
{
    ll tp;
    while(b)
      {tp=a%b;a=b;b=tp;}
    return a;
}
inline bool Check(ll p)
{
    if(p<=maxn)
      return !check[p];
    if(!(p&1))return false;
    ll a=rand()%p;
    if(pow(a,p-1,p)!=1)return false;
    ll j=lowbit(p-1),m=(p-1)/j,b=rand()%(p-4)+2,v=pow(b,m,p);
    if(v==1)return true;
    j>>=1;
    while(j)
    {
        if(v==p-1||v==1)return true;
        v=mult(v,v,p);
        j>>=1;
    }
    return false;
}
 
char c;
inline void read(ll &a)
{a=0;do c=getchar();while(c<'0'||c>'9');while(c<='9'&&c>='0')a=(a<<3)+(a<<1)+c-'0',c=getchar();}
inline ll f(ll a,ll n)
{return mult(a,a,n);}
 
inline ll Rho(ll n)
{
     
    if(n==1)return 1;
    ll k=2,x=rand()%n,y=x,p=1,c=rand()%(n-1)+1;
    for(ll i=1;p==1;i++)
    {
        x=(mult(x,x,n)+c)%n;
        p=abs(x-y);
        p=gcd(n,p);
        if(i==k) y=x,k<<=1;
    }
    return p;
}
 
void fact(ll n)
{
    if(n==1)return;
    if(Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n))
       factor[++tot]=n;
    else
      {
          ll p=Rho(n);fact(n/p);fact(p);
      }
}
 
int main()
{
    int i,j;
    srand(10086);
    check[1]=true;
    check[0]=true;
    for(i=2;i<maxn;i++)
     {
        if(!check[i]) prime[++tot]=i;
        for(j=1;j<=tot;j++)
          if(prime[j]*1ll*i>maxn)break;
          else if(i%prime[j]==0){check[prime[j]*i]=true;break;}
          else
            check[prime[j]*i]=true;
     }
     ll T,tp;
     ll n;
    read(T);
    while(T--)
    {
        read(n);tp=n;
        if(Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n)&&Check(n))
           puts("Prime");
        else
        {
            tot=0;
            fact(tp);
            ll ans=-1;
            if(tot==1){         puts("Prime");continue;}
            for(i=1;i<=tot;i++)
               if(ans<factor[i])ans=factor[i];
            printf("%lld\n",ans);
            if(ans==1781707)
            ans++;
        }
    }
    return 0;
}