/* Generates all possible placements of n non-attacking rooks on an nxn board. 
   In other words, all permutations of 1 .. n. */

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

#define MAX 12


int n;

int A[MAX];
int sol[MAX];

void Print() {
  int i;

  for (i=0; i < n; i ++)
    printf(" %2d", sol[i] + 1);

  printf("\n");
}

void Rook(int col) {
  int row;

  for (row=0; row < n; row ++) {
    if (A[row]) {
	sol[col] = row;
	A[row] = 0;
	if (col < n-1)
	  Rook(col+1);
	else
	  Print();
	A[row] = 1;
      }
  }
}

int main(int argc, char *argv[]) {
  int i;

    if (argc != 2) {
    printf("\n A single argument expected.\n");
    return 1;
  }

  n = atoi(argv[1]);


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

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

  for (i=0; i < n; i ++) A[i] = 1;
  
  Rook(0);

  return 0;
}