/* Algorithm 4.6 in Ruskey's textbook: Recursive procedure for generating B(n, k) in colex order. */

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

#define MAX 50

int size;

void PrintIt(int Array[]) {
  int i;
  
  for (i = 0; i < size; i ++) printf(" %d", Array[i]);

  printf("\n");
}

void Combs(int Array[], int n, int k) {
  int i;

  if (n == 0)
    PrintIt(Array);
  else {
    if (k < n) {
      Array[n-1] = 0;
      Combs(Array, n-1, k);
    }
    if (k > 0) {
      Array[n-1] = 1;
      Combs(Array, n-1, k-1);
    }
  }
}

int main(int argc, char *argv[]) {
  int n, k, i;
  int B[MAX];
  
  if (argc != 3) {
    printf("\n Two arguments expected.\n");
    return 1;
  }

  k = atoi(argv[1]);
  n = atoi(argv[2]);

  if (n < 0 || k < 0) {
    printf("\n Positive numbers expected.\n");
    return 2;
  }

  if (n > MAX || k > MAX) {
    printf("\n Numbers not greater than %d expected.\n", MAX);
    return 3;
  }

  if (k > n) {
    printf("\n The first number must not be greater than the second number.\n");
    return 4;
  }

  size = n;
  
  Combs(B, n, k);
  
  return 0;
}