/*
 * @(#)EQSortAlgorithm.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 enhanced quick sort demonstration algorithm
 * SortAlgorithm.java, Thu Oct 27 10:32:35 1994
 *
 * @author Jim Boritz
 * @version 	1.0, 26 Jun 1995
 */
/**
 * 19 Feb 1996: Fixed to avoid infinite loop discoved by Paul Haberli.
 *              Misbehaviour expressed when the pivot element was not unique.
 *              -Jason Harrison
 *
 * 21 Jun 1996: Modified code based on comments from Paul Haeberli, and
 *              Peter Schweizer (Peter.Schweizer@mni.fh-giessen.de).  
 *              Used Daeron Meyer's (daeron@geom.umn.edu) code for the
 *              new pivoting code. - Jason Harrison
 *
 * 09 Jan 1998: Another set of bug fixes by Thomas Everth (everth@wave.co.nz)
 *              and John Brzustowski (jbrzusto@gpu.srv.ualberta.ca).
 *              
 * 27 Nov 2006: (bwbecker@uwaterloo.ca) Changed the overall architecture to
 * use model-view-controller.  Re-examined algorithm to ensure that counting
 * was consistent across all algorithms (the quicksorts used to ignore most
 * of the comparisons in the partitioning, for example).
 */
class EQSortAlgorithm extends SortAlgorithm
{
	void brute(int a[], int lo, int hi)
	{
		super.lowMarker = lo;
		super.hiMarker = hi;
		if ((hi - lo) == 1)
		{
			super.compares++;
			if (a[hi] < a[lo])
			{
				int T = a[lo];
				a[lo] = a[hi];
				a[hi] = T;
				super.moves++;
				super.updateAllViews();
			}
		}
		if ((hi - lo) == 2)
		{
			int pmin = a[lo] < a[lo + 1] ? lo : lo + 1;
			pmin = a[pmin] < a[lo + 2] ? pmin : lo + 2;
			super.compares += 2;
			if (pmin != lo)
			{
				int T = a[lo];
				a[lo] = a[pmin];
				a[pmin] = T;
				super.moves++;
			}
			super.updateAllViews();
			brute(a, lo + 1, hi);
		}
		if ((hi - lo) == 3)
		{
			int pmin = a[lo] < a[lo + 1] ? lo : lo + 1;
			pmin = a[pmin] < a[lo + 2] ? pmin : lo + 2;
			pmin = a[pmin] < a[lo + 3] ? pmin : lo + 3;
			super.compares += 3;
			if (pmin != lo)
			{
				int T = a[lo];
				a[lo] = a[pmin];
				a[pmin] = T;
				super.moves++;
			}
			super.updateAllViews();
			int pmax = a[hi] > a[hi - 1] ? hi : hi - 1;
			pmax = a[pmax] > a[hi - 2] ? pmax : hi - 2;
			super.compares += 2;
			if (pmax != hi)
			{
				int T = a[hi];
				a[hi] = a[pmax];
				a[pmax] = T;
				super.moves++;
			}
			super.updateAllViews();
			brute(a, lo + 1, hi - 1);
		}
	}

	void sort(int a[], int lo0, int hi0)
	{
		int lo = lo0;
		int hi = hi0;
		super.lowMarker = lo;
		super.hiMarker = hi;
		if ((hi - lo) <= 3)
		{
			brute(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;
		super.other += 3;
		
		while (lo < hi)
		{
			/*
			 *  Search forward from a[lo] until an element is found that
			 *  is greater than the pivot or lo >= hi 
			 */
			super.compares++;
			while (a[lo] <= pivot && lo < hi)
			{
				lo++;
				super.compares++;
			}

			/*
			 *  Search backward from a[hi] until element is found that
			 *  is less than the pivot, or hi <= lo 
			 */
			super.compares++;
			while (pivot <= a[hi] && lo < hi)
			{
				hi--;
				super.compares++;
			}

			/*
			 *  Swap elements a[lo] and a[hi]
			 */
			if (lo < hi)
			{
				int T = a[lo];
				a[lo] = a[hi];
				a[hi] = T;
				super.moves++;
				super.updateAllViews();
			}
		}

		if (stopRequested)
		{
			return;
		}

		/*
		 *  Put the median in the "center" of the list
		 */
		a[hi0] = a[hi];
		a[hi] = pivot;
		super.moves += 2;
		super.updateAllViews();

		/*
		 *  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);
	}

	void sort(int a[])
	{
		sort(a, 0, a.length - 1);
		super.updateAllViews(-1, -1);
	}
}