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

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

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


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

/**
 * Count how many times val appears in the first size elements of vals. 
 */
static int
ia_tally (int vals[], int size, int val)
{
  int i;
  int tally = 0;
  for (i = 0; i < size; i++)
    if (vals[i] == val)
      ++tally;
  return tally;
} // ia_tally


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

int
ia_is_permutation (int a0[], int a1[], int size)
{
  int i;
  // For each element in a0
  for (i = 0; i < size; i++)
    {
      // Make sure that the element appears the same number of times in 
      // a0 and a1.
      if (ia_tally (a0, size, a0[i]) != ia_tally (a1, size, a0[i]))
        return 0;
    } // for
  // If all tallies are equal, the two arrays are permutations
  return 1;
} // ia_is_permutation