/*
 * @(#)BidirectionalBubbleSortAlgorithm.java	1.6f 95/01/31 James Gosling
 *
 * Copyright (c) 1994-1995 Sun Microsystems, Inc. All Rights Reserved.
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 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
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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
 *
 * Modified by Istvan Simon, Feb 18, 1996
 *	Now draws water marks before it starts to sort and moves first high water mark,
 *	then low water mark at each iteration, as it should. Also pauses for each comparison, not just each flip.
 */
class BidirectionalBubbleSortAlgorithm extends SortAlgorithm {
    void sort(int a[]) throws Exception {
	int j;
	int limit = a.length;
	int st = -1;
	pause(st+1,limit-1); // Draw water marks before item 0 and after item (a.length-1)
	while (st < limit) {
	    boolean flipped = false;
	    st++;
	    limit--;
	    for (j = st; j < limit; j++) {
		if (stopRequested) {
		    return;
		}
		if (a[j] > a[j + 1]) {
		    int T = a[j];
		    a[j] = a[j + 1];
		    a[j + 1] = T;
		    flipped = true;
		}
		pause(st, limit);

	    }
	    if (!flipped) {
		return;
	    }
	    pause(st,limit-1);
	    for (j = limit; --j >= st;) {
		if (stopRequested) {
		    return;
		}
		if (a[j] > a[j + 1]) {
		    int T = a[j];
		    a[j] = a[j + 1];
		    a[j + 1] = T;
		    flipped = true;
		}
	 	pause(st, limit-1);

	    }
	    if (!flipped) {
		return;
	    }
	    pause(st+1,limit-1);
	}
	pause(st, limit);
    }
}