/*
 * @(#)BidirectionalBubbleSortAlgorithm.java	1.6f 95/01/31 James Gosling
 *
 * Copyright (c) 1994-1995 Sun Microsystems, Inc. All Rights Reserved.
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 * without fee is hereby granted. 
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 * 
 * SUN 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. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 * 
 * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
 * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE
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 */

/**
 * A bi-directional bubble sort demonstration algorithm
 * SortAlgorithm.java, Thu Oct 27 10:32:35 1994
 *
 * @author James Gosling
 * @version 	1.6f, 31 Jan 1995
 * 
 * 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 BidirectionalBubbleSortAlgorithm extends SortAlgorithm
{
	void sort(int a[])
	{
		int j;
		int limit = a.length;
		int st = -1;
		while (st < limit)
		{
			boolean flipped = false;
			st++;
			limit--;
			super.updateAllViews(st, limit+1);
			
			// Swap larger elements to the right.
			for (j = st; j < limit; j++)
			{
				if (stopRequested)
				{
					return;
				}
				super.compares++;
				super.activeMarker = j;
				if (a[j] > a[j + 1])
				{
					int T = a[j];
					a[j] = a[j + 1];
					a[j + 1] = T;
					flipped = true;
					super.moves++;
					super.updateAllViews();
				}
			}
			super.hiMarker = limit;
			if (!flipped)
			{
				super.updateAllViews(-1, -1);
				return;
			}
			
			// Swap smaller elements to the left.
			for (j = limit; --j >= st;)
			{
				if (stopRequested)
				{
					return;
				}
				super.compares++;
				super.activeMarker = j;
				if (a[j] > a[j + 1])
				{
					int T = a[j];
					a[j] = a[j + 1];
					a[j + 1] = T;
					flipped = true;
					super.moves++;
					super.updateAllViews();
				}
			}
			if (!flipped)
			{
				super.updateAllViews(-1, -1);
				return;
			}
		}
		
		super.updateAllViews(-1, -1);
	}
}