poj 2409 polya定理

polya定理的入门题

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

int pow( int a, int n )
{
  int r = 1;
  while ( n-- )
  {
    r = r * a;
  }
  return r;
}

int gcd( int a, int b )
{
  if ( b )
  {
    return gcd( b, a % b );
  }
  return a;
}

int main ()
{
  int c, s;
  while ( scanf("%d%d", &c, &s), c + s )
  {
    int sum = 0;
    for ( int i = 1; i <= s; i++ )
    {
      int tmp = gcd( i, s );
      sum += pow( c, tmp );
    }
    if ( s & 1 )
    {
      sum += s * pow( c, ( s + 1 ) / 2 );
    }
    else
    {
      sum += ( s / 2 ) * ( pow( c, ( s / 2 ) + 1 ) + pow( c, ( s / 2 ) ) );
    }
    sum /= s * 2;
    printf("%d\n", sum);
  }
    return 0;
}