hdu 4529 Double Dealing (置换群)

# include <stdio.h>

# include <algorithm>

# include <string.h>

using namespace std;

__int64 gcd(__int64 a,__int64 b)

{

    if(b==0)

        return a;

    return gcd(b,a%b);

}

int main()

{

    int n,k,i,j,vis[810],m,num[810],x;

    __int64 res,cot;

    while(~scanf("%d%d",&n,&k),n+k)

    {

        m=1;

        for(i=1; i<=k&&i<=n; i++) //第一次分完牌

            for(j=(n-i)/k*k+i; j>0; j-=k)

                num[m++]=j;

        res=1;

        memset(vis,0,sizeof(vis));

        for(i=1; i<=n; i++)

        {

            if(vis[i])

                continue;

            x=i;

            cot=0;

            while(1)

            {

                vis[x]=1;

                cot++;

                x=num[x];

                if(i==x)

                    break;

            }

            res=res/gcd(res,cot)*cot;

        }

        printf("%I64d\n",res);

    }

    return 0;

}