/*
 * 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 2 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * This program demonstrates the use of the quick sort algorithm.  For
 * more information about this and other sorting algorithms, see
 * http://linux.wku.edu/~lamonml/kb.html
 *
 */
 
/*******
 * Jim M:
 *  from http://linux.wku.edu/~lamonml/algor/sort/quick.html on 2/14/2007
 *
 * This version is designed to be used with qs_main.c .
 *
 **********
 */

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

#include "qs.h"

long count;

// return how many steps the quicksort took
long quickSort(int numbers[], int array_size){
  count = 0;
  q_sort(numbers, 0, array_size - 1);
  return count;
}

void q_sort(int numbers[], int left, int right){
  int pivot, l_hold, r_hold;

  l_hold = left;
  r_hold = right;
  pivot = numbers[left];
  while (left < right) {
    while ((numbers[right] >= pivot) && (left < right) && count++>=0){
      right--;
    }
    if (left != right) {
      numbers[left] = numbers[right];
      left++;
    }
    while ((numbers[left] <= pivot) && (left < right) && count++>=0){
      left++;
    }
    if (left != right) {
      numbers[right] = numbers[left];
      right--;
    }
  }
  numbers[left] = pivot;
  pivot = left;
  left = l_hold;
  right = r_hold;
  if (left < pivot){
    q_sort(numbers, left, pivot-1);
  }
  if (right > pivot){
    q_sort(numbers, pivot+1, right);
  }
}