/*
 * @(#)MergeSortAlgorithm.java   1.0 95/06/23 Jason Harrison
 *
 * Copyright (c) 1995 University of British Columbia
 *
 * 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.
 */

/** A merge sort demonstration algorithm. <br />
 *  <br />
 *  Author Jason Harrison, his version 1.1, 12 Jan 1998<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 MergeSortAlgorithm extends SortApplet.SortAlgorithm {
   
   void sort(int[] a, int lo0, int hi0)  {
      int lo = lo0;
      int hi = hi0;
      pause(lo, hi);
      if (lo >= hi)  return;
      int mid = (lo + hi) / 2;
      
      // Partition the list into two lists and sort them recursively
      sort(a, lo, mid);
      sort(a, mid + 1, hi);
      
      //  Merge the two sorted lists
      int end_lo = mid;
      int start_hi = mid + 1;
      while ((lo <= end_lo) && (start_hi <= hi)) {
         pause(lo);
         if (stopRequested) return; // Abbruch
          if (a[lo] < a[start_hi]) {
            ++lo;
         } else {
            /*  a[lo] >= a[start_hi]
             *  The next element comes from the second list, 
             *  move the a[start_hi] element into the next 
             *  position and shuffle all the other elements up.
             */
            int temp = a[start_hi];
            for (int k = start_hi - 1; k >= lo; --k) {
               a[k+1] = a[k];
               pause(lo);
            }
            a[lo] = temp;
            ++lo;
            ++end_lo;
            ++start_hi;
         }
      }
   }
   
   @Override void sort(int[] a) {
      sort(a, 0, a.length-1);
   } // sort(int[])
   
} // class MergeSortAlgorithm