快速幂模板

// m^n % k

int quickpow(int m,int n,int k)

{

    int b = 1;

    while (n > 0)

    {

          if (n & 1)

             b = (b*m)%k;

          n = n >> 1 ;

          m = (m*m)%k;

    }

    return b;

}