/*
 * @(#)QubbleSortAlgorithm.java   1.0 95/06/26 Jim Boritz
 *
 * Copyright (c) 1995 UBC Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * UBC MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. UBC SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

/** An quick sort with buble sort speedup  demonstration algorithm. <br />
 *  <br />
 *  Author Jim Boritz, his version 1.6, 26 Jun 1995<br />
 *  <br />
 *  19 Feb 1996: Fixed to avoid infinite loop discovered by Paul Haeberli.
 *          Misbehaviour expressed when the pivot element was not unique.<br />
 *  <br />
 *  Modif. 15.11.2005, Albrecht Weinert (a-weinert.de) :<br />
 *  {@link SortApplet.SortAlgorithm} + Kleinigkeiten.<br />  
 *  <br />
 *  @author   Albrecht Weinert
 *  @version  V.161, 28.05.2011
 */
public final class QubbleSortAlgorithm extends SortApplet.SortAlgorithm {

   void bSort(int[] a, int lo, int hi){
      for (int j=hi; j > lo; j--) {
         for (int i=lo; i < j; i++) {
            if (a[i] > a[i+1]) {
               int T = a[i];
               a[i] = a[i+1];
               a[i+1] = T;
               pause();
            }
         }
      }
   } // bSort(int[], 2*int)
   
   void sort(int[] a, int lo0, int hi0)  {
      int lo = lo0;
      int hi = hi0;
      pause(lo, hi);
      //  Bubble sort if the number of elements is less than 6 
      if (hi -lo <= 6) {
         bSort(a, lo, hi);
         return;
      }
      
      //  Pick a pivot and move it out of the way
      int pivot = a[(lo + hi) / 2];
      a[(lo + hi) / 2] = a[hi];
      a[hi] = pivot;
      
      while( lo < hi ) {
         /* Search forward from a[lo] until an element is found that
          *  is greater than the pivot or lo >= hi  */
         while (a[lo] <= pivot && lo < hi) {   ++lo;   }
         
         /* Search backward from a[hi] until element is found that
          *  is less than the pivot, or hi <= lo   */
         while (pivot <= a[hi] && lo < hi ) { --hi;  }
         
         // Swap elements a[lo] and a[hi]
         if( lo < hi ) {
            int temp = a[lo];
            a[lo] = a[hi];
            a[hi] = temp;
            pause();
         }
      }
      
      //  Put the median in the "center" of the list
      a[hi0] = a[hi];
      a[hi] = pivot;
      
      /* Recursive calls, elements a[lo0] to a[lo-1] are less than or
       *  equal to pivot, elements a[hi+1] to a[hi0] are greater than
       *  pivot. */
      sort(a, lo0, lo-1);
      sort(a, hi+1, hi0);
   } // sort(int[], 2*int)
   
   @Override void sort(int[] a) {
      sort(a, 0, a.length-1);
   } // sort(Int[])
   
}