快速排序算法

package Alg;



import java.util.Random;



public class QuickSort {

	public static void quickSort(int[] ary) {

		quickSort(ary, 0, ary.length - 1);

	}

	

	/**

	 * @param ary 数组 排序数组

	 * @param start 开始位置 ，0-base index

	 * @param end 结束位置，0-base index

	 */

	private static void quickSort(int[] ary, int start, int end) {

		if (start < end) {

			int p = partition(ary, start, end);

			quickSort(ary, start, p - 1);

			quickSort(ary, p + 1, end);

		}

	}

	

	private static int partition(int[] ary, int start, int end) {

		int pivot = start, i = start, j = start + 1;

		for (; j <= end; j++) {

			if (ary[j] < ary[pivot]) {

				i++;

				if (i == j)

					continue;

				int temp = ary[i];

				ary[i] = ary[j];

				ary[j] = temp;

			}

		}

		int temp = ary[pivot];

		ary[pivot] = ary[i];

		ary[i] = temp;

		return i;

	}

	

	public static void testCase1() {

		int length = 15;

//		int[] ary = new int[] {956,683,804,133,174,595,483,834,713,433,827,253,752,62,73};

		int[] ary = new int[length];

		java.util.Random rand = new Random();

		for (int i = 0; i < length; i++) {

			ary[i] = Math.abs(rand.nextInt()) % 1000;

		}

		

		for (int i = 0; i < length; i++)

			System.out.print(ary[i] + ",");

		

		System.out.println();

		

		quickSort(ary);

		

		for (int i = 0; i < length; i++)

			System.out.print(ary[i] + ",");

		

		System.out.println();

	}

}