usaco 2.1 hamming...枚举...

因为要求最终序列化为2^B进制数后最小，所以最小从0开始一一枚举&检验即可。

/*
    ID:chenjiong
    PROG:hamming
    LANG:C++
*/

#include <stdio.h>
#include <string.h>

int N,B,D;

int ans[64][9];      
int num;
int limit[9] = {0,1,3,7,15,31,63,127,255};

int cnt;
void binary(int x,int* tmp)
{
    tmp[cnt++] = x % 2;
    if ( x > 0 )
        binary( x / 2,tmp);
}

int hamming_distance(int i,int j)
{
    int d = 0;
    int k;
    for ( k = 0; k < 8; k++)
        if ( ans[i][k] != ans[j][k] )
            d++;
    return d;
}

int is_accepted(int cur)
{
    int i;
    for ( i = cur - 1; i >= 0; i--)
        if ( hamming_distance(i,cur) < D )
            return false;
    return true;
}

int main()
{
    freopen("hamming.in","r",stdin);
    freopen("hamming.out","w",stdout);

    scanf("%d%d%d",&N,&B,&D);
    
    num = 1;
    int x;
    for ( x = 1; x <= limit[B]; x++)
    {
        cnt = 0;
        binary(x,ans[num]);
        ans[num][8] = x;

        if ( is_accepted(num) )
            num++;
        if ( num == N )
            break;
    }

    int t = 0;
    int i;
    for ( i = 0; i < N - 1; i++)
    {
        printf("%d ",ans[i][8]);
        t++;
        if ( t == 9 && i < N - 2 )
        {
            printf("%d\n",ans[++i][8]);
            t = 0;
        }
    }
    printf("%d\n",ans[N - 1][8]);

    return 0;
}