/* multiset/multiset.c

 * based on combination/combination.c by Szymon Jaroszewicz

 * based on permutation/permutation.c by Brian Gough

 *

 * Copyright (C) 2001 Szymon Jaroszewicz

 * Copyright (C) 2009 Rhys Ulerich

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or (at

 * your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 */

#include <config.h>

#include <gsl/gsl_errno.h>

#include <gsl/gsl_multiset.h>

size_t

gsl_multiset_n (const gsl_multiset * c)

{

  return c->n ;

}

size_t

gsl_multiset_k (const gsl_multiset * c)

{

  return c->k ;

}

size_t *

gsl_multiset_data (const gsl_multiset * c)

{

  return c->data ;

}

int

gsl_multiset_valid (gsl_multiset * c)

{

  const size_t n = c->n ;

  const size_t k = c->k ;

  size_t i, j ;

  for (i = 0; i < k; i++)

    {

      const size_t ci = c->data[i];

      if (ci >= n)

        {

          GSL_ERROR("multiset index outside range", GSL_FAILURE) ;

        }

      for (j = 0; j < i; j++)

        {

          if (c->data[j] > ci)

            {

              GSL_ERROR("multiset indices not in increasing order",

                        GSL_FAILURE) ;

            }

        }

    }

  return GSL_SUCCESS;

}

int

gsl_multiset_next (gsl_multiset * c)

{

  /* Replaces c with the next multiset (in the standard lexicographical

   * ordering).  Returns GSL_FAILURE if there is no next multiset.

   */

  const size_t n = c->n;

  const size_t k = c->k;

  size_t *data = c->data;

  size_t i;

  if(k == 0)

    {

      return GSL_FAILURE;

    }

  i = k - 1;

  while(i > 0 && data[i] == n-1)

    {

      --i;

    }

  if (i == 0 && data[0] == n-1)

    {

      return GSL_FAILURE;

    }

  ++data[i];

  while(i < k-1)

    {

      data[i+1] = data[i];

      ++i;

    }

  return GSL_SUCCESS;

}

int

gsl_multiset_prev (gsl_multiset * c)

{

  /* Replaces c with the previous multiset (in the standard

   * lexicographical ordering).  Returns GSL_FAILURE if there is no

   * previous multiset.

   */

  const size_t n = c->n;

  const size_t k = c->k;

  size_t *data = c->data;

  size_t i;

  if(k == 0)

    {

      return GSL_FAILURE;

    }

  i = k - 1;

  while(i > 0 && data[i-1] == data[i])

    {

      --i;

    }

  if(i == 0 && data[i] == 0)

    {

      return GSL_FAILURE;

    }

  data[i]--;

  if (data[i] < n-1)

    {

      while (i < k-1) {

        data[++i] = n - 1;

      }

    }

  return GSL_SUCCESS;

}

int

gsl_multiset_memcpy (gsl_multiset * dest, const gsl_multiset * src)

{

   const size_t src_n = src->n;

   const size_t src_k = src->k;

   const size_t dest_n = dest->n;

   const size_t dest_k = dest->k;

   if (src_n != dest_n || src_k != dest_k)

     {

       GSL_ERROR ("multiset lengths are not equal", GSL_EBADLEN);

     }

   {

     size_t j;

     for (j = 0; j < src_k; j++)

       {

         dest->data[j] = src->data[j];

       }

   }

   return GSL_SUCCESS;

}