#include <time.h>
#include <stdio.h>
#include <stdlib.h>

extern const char *__progname;

static int codelen;
static int mindist;

static unsigned int codes[16777216];
static unsigned int codemask;
static int listsize;
static int nchosen;

static void genlist(void)
{
 int i;
 int j;
 unsigned int t;

 listsize = 1 << codelen;
 codemask = listsize - 1;
 for (i=codemask;i>=0;i--) codes[i] = i;
 for (i=codemask;i>=0;i--)
  { j = random() & codemask;
    if (i != j)
     { t = codes[i];
       codes[i] = codes[j];
       codes[j] = t;
     }
  }
 nchosen = 0;
}

static void print(unsigned int c)
{
 int i;

 for (i=codelen-1;i>=0;i--) printf("%d",(c>>i)&1);
 printf("\n");
}

static int hamdist(unsigned int a, unsigned int b)
{
 a ^= b;
 a = ((a >> 1) & 0x55555555) + (a & 0x55555555);
 a = ((a >> 2) & 0x33333333) + (a & 0x33333333);
 a = ((a >> 4) & 0x0f0f0f0f) + (a & 0x0f0f0f0f);
 a = ((a >> 8) & 0x00ff00ff) + (a & 0x00ff00ff);
 return(((a>>16)&0x0000ffff)+(a&0x0000ffff));
}

static void filter(unsigned int c)
{
 int i;
 int j;

 j = nchosen;
 for (i=nchosen;i<listsize;i++)
  { if (hamdist(codes[i],c) >= mindist)
     { if (j != i) codes[j] = codes[i];
       j ++;
     }
  }
 listsize = j;
}

int main(int, char **);
int main(int ac, char **av)
{
 if (ac != 3)
  { fprintf(stderr,"Usage: %s code-length min-Hamming-distance\n",__progname);
    exit(1);
  }
 codelen = atoi(av[1]);
 mindist = atoi(av[2]);
 if (codelen < 2)
  { fprintf(stderr,"%s: min code length is 2\n",__progname);
    exit(1);
  }
 if (codelen > 24)
  { fprintf(stderr,"%s: max code length is 24\n",__progname);
    exit(1);
  }
 srandom(time(0));
 genlist();
 while (listsize > nchosen)
  { nchosen ++;
    print(codes[nchosen-1]);
    filter(codes[nchosen-1]);
  }
 return(0);
}