usaco 2.1 hamming...枚举...

/*
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;
}