POJ 1811 Prime Test

POJ 1811 Prime Test

模板题。Pollard Rho大整数分解质因数。
以下是我的代码：

#include < iostream >
#include < cstdio >
#include < cstdlib >
#include < ctime >
#define  Random(n) (rand()%(n+1))
using   namespace  std;
typedef  long   long  int64;
const   int  kMaxT( 7 );
int  cnt,factor[ 107 ];

int64 Gcd(int64 a,int64 b)
{
     for (int64 t = a % b;t;a = b,b = t,t = a % b); return  abs(b);
}

int64 MutiMod(int64 a,int64 b,int64 n)
{
    int64 exp(a % n),res( 0 );
     while (b)
    {
         if (b & 1 )
        {
            res += exp;
             if (res > n)
                res -= n;
        }
        exp <<= 1 ;
         if (exp > n)
            exp -= n;
        b >>= 1 ;
    }
     return  res;
}

int64 ExpMod(int64 a,int64 n,int64 b)
{
    int64 r( 1 ),t(a % b);
     if (n == 0 )  return   1 % b;
     while (n > 1 )
    {
         if (n & 1 )
            r = MutiMod(r,t,b);
        t = MutiMod(t,t,b);
        n >>= 1 ;
    }
     return  MutiMod(r,t,b);
}

bool  MillerRabbin(int64 n)
{
     if (n == 2 )
         return   true ;
     if (n < 2   ||   ! (n & 1 ))
         return   false ;

    int64 a,u(n - 1 ),x,y;
     int  t( 0 );
     while (u % 2 == 0 )
    {
        t ++ ;
        u >>= 1 ;
    }

    srand(time(NULL));
     for ( int  i = 1 ;i <= kMaxT;i ++ )
    {
        a = Random(n - 2 ) + 1 ;
        x = ExpMod(a,u,n);
         for ( int  j = 0 ;j < t;j ++ )
        {
            y = MutiMod(x,x,n);
             if (y == 1   &&  x != 1   &&  x != n - 1 )
                 return   false ;
            x = y;
        }
         if (y != 1 )
             return   false ;
    }
     return   true ;
}

int64 PollardRho(int64 n, int  c)
{
    int64 x(Random(n - 2 ) + 1 ),y(x),d,i( 1 ),k( 2 );
     while ( true )
    {
        i ++ ;
        x = (MutiMod(x,x,n) + c) % n;
        d = Gcd(y - x,n);
         if (d > 1   &&  d < n)
             return  d;
         if (x == y)
             return  n;
         if (i == k)
        {
            y = x;
            k <<= 1 ;
        }
    }
}

void  FindFactor(int64 n, int  k)
{
     if (n == 1 )
         return ;
     if (MillerRabbin(n))
    {
        factor[ ++ cnt] = n;
         return ;
    }
    int64 p(n);
     while (p >= n)
        p = PollardRho(p,k -- );
    FindFactor(p,k);
    FindFactor(n / p,k);
}

int  main()
{
     int  T;
    cin >> T;
     while (T -- )
    {
        int64 n;
        cin >> n;
        cnt =- 1 ;
        FindFactor(n, 107 );
         if (cnt == 0 )
            cout << " Prime " << endl;
         else
        {
             int  min( - 1 );
             for ( int  i = 0 ;i <= cnt;i ++ )
                 if (min < 0   ||  min > factor[i])
                    min = factor[i];
            cout << min << endl;
        }
    }

     return   0 ;
}