| /* |
| * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * - Neither the name of Oracle nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| */ |
| |
| /** |
| * A quick sort demonstration algorithm |
| * SortAlgorithm.java |
| * |
| * @author James Gosling |
| * @author Kevin A. Smith |
| */ |
| public class QSortAlgorithm extends SortAlgorithm |
| { |
| |
| /** |
| * A version of pause() that makes it easier to ensure that we pause |
| * exactly the right number of times. |
| */ |
| private boolean pauseTrue(int lo, int hi) throws Exception { |
| super.pause(lo, hi); |
| return true; |
| } |
| |
| /** This is a generic version of C.A.R Hoare's Quick Sort |
| * algorithm. This will handle arrays that are already |
| * sorted, and arrays with duplicate keys.<BR> |
| * |
| * If you think of a one dimensional array as going from |
| * the lowest index on the left to the highest index on the right |
| * then the parameters to this function are lowest index or |
| * left and highest index or right. The first time you call |
| * this function it will be with the parameters 0, a.length - 1. |
| * |
| * @param a an integer array |
| * @param lo0 left boundary of array partition |
| * @param hi0 right boundary of array partition |
| */ |
| void QuickSort(int a[], int lo0, int hi0) throws Exception |
| { |
| int lo = lo0; |
| int hi = hi0; |
| int mid; |
| |
| if ( hi0 > lo0) |
| { |
| |
| /* Arbitrarily establishing partition element as the midpoint of |
| * the array. |
| */ |
| mid = a[ ( lo0 + hi0 ) / 2 ]; |
| |
| // loop through the array until indices cross |
| while( lo <= hi ) |
| { |
| /* find the first element that is greater than or equal to |
| * the partition element starting from the left Index. |
| */ |
| while( ( lo < hi0 ) && pauseTrue(lo0, hi0) && ( a[lo] < mid )) |
| ++lo; |
| |
| /* find an element that is smaller than or equal to |
| * the partition element starting from the right Index. |
| */ |
| while( ( hi > lo0 ) && pauseTrue(lo0, hi0) && ( a[hi] > mid )) |
| --hi; |
| |
| // if the indexes have not crossed, swap |
| if( lo <= hi ) |
| { |
| swap(a, lo, hi); |
| ++lo; |
| --hi; |
| } |
| } |
| |
| /* If the right index has not reached the left side of array |
| * must now sort the left partition. |
| */ |
| if( lo0 < hi ) |
| QuickSort( a, lo0, hi ); |
| |
| /* If the left index has not reached the right side of array |
| * must now sort the right partition. |
| */ |
| if( lo < hi0 ) |
| QuickSort( a, lo, hi0 ); |
| |
| } |
| } |
| |
| private void swap(int a[], int i, int j) |
| { |
| int T; |
| T = a[i]; |
| a[i] = a[j]; |
| a[j] = T; |
| |
| } |
| |
| public void sort(int a[]) throws Exception |
| { |
| QuickSort(a, 0, a.length - 1); |
| } |
| } |