/**
 * perm.c
 *   Definitions of functions useful for checking permutations.
 */

// +---------+--------------------------------------------------------
// | Headers |
// +---------+

#include "perm.h"
#include "bool.h"


// +---------+--------------------------------------------------------
// | Helpers |
// +---------+

/**
 * Check off one copy of val from vals, assuming that the elements of
 * checkmarks indicate whether or not we've checked off the corresponding
 * value in vals.
 */
static int
check_off (int vals[], int checkmarks[], int size, int val)
{
  int i;
  for (i = 0; i < size; i++)
    {
      if ((! checkmarks[i]) && (vals[i] == val))
        {
          checkmarks[i] = 1;
          return 1;
        }
    } // for
  // If we've gotten this far, we didn't check anything off
  return 0;
} // check_off


// +--------------------+---------------------------------------------
// | Exported Functions |
// +--------------------+

int
ia_is_permutation (int a0[], int a1[], int size)
{
  int checkmarks[size];
  int i;

  // Initially, nothing is marked
  for (i = 0; i < size; i++)
    checkmarks[i] = 0;

  // For each element of a0
  for (i = 0; i < size; i++)
    {
      // Try to check it off in a1
      if (! check_off (a1, checkmarks, size, a0[i]))
        return 0;
    } // for

  // Yay!  We checked off every element.  We're done
  return 1;
} // ia_is_permutation