快速排序

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package com.cdl.algorithem;

import java.util.Arrays;
import java.util.Random;

/**
 * 参考：

 * 1.http://www.iteye.com/topic/805043

 * 2.视频：舞动的排序算法 快速排序 http://www.56.com/u61/v_NjczMjQ5Nzg.html

 * 3.视频： 动画http://video.sina.com.cn/v/b/43015877-1731942570.html

 * 
 * @author [email protected]
 * @date: 2011-4-30
 */
public class QickSortTest {

	public static void main(String[] args) {
		int[] emptyArray = new int[10];// 定义一个数组
		int[] targetArray = initArray(emptyArray);// 初始化数组
		qickSort(targetArray, 0, targetArray.length - 1);// 排序数组
		System.out.println("排序后的数组：" + Arrays.toString(targetArray));// 打印最后的数组

	}

	/** 初始化数组：使用随机数为数组赋值 */
	private static int[] initArray(int[] array) {
		Random random = new Random();
		for (int i = 0; i < array.length; i++) {
			array[i] = random.nextInt(100) - random.nextInt(100);
		}
		System.out.println("排序前的数组：" + Arrays.toString(array));
		return array;
	}

	/** 交换两索引处的值 */
	private static void swap(int[] array, int oneIndex,
			int anotherIndex) {
		int tempValue = array[oneIndex];
		array[oneIndex] = array[anotherIndex];
		array[anotherIndex] = tempValue;
	}

	/** 对某一次找出中轴的排序 */
	private static int sortOnce(int[] array, int lowIndex, int highIndex) {

		int pivotIndex = lowIndex;
		int pivotValue = array[pivotIndex];

		while (lowIndex < highIndex) {
			while (lowIndex < highIndex && pivotValue <= array[highIndex]) {
				highIndex--;
			}
			swap(array, pivotIndex, highIndex);
			pivotIndex = highIndex;

			while (lowIndex < highIndex && array[lowIndex] <= pivotValue) {
				lowIndex++;
			}
			swap(array, lowIndex, pivotIndex);
			pivotIndex = lowIndex;
		}
		return pivotIndex;
	}

	/**
	 * 递归进行排序

	 * 找出中轴后然后分治成两组,分别再次递归

	 * */
	private static void qickSort(int[] array, int lowIndex, int highIndex) {
		if (lowIndex < highIndex) {
			int privotIndex = sortOnce(array, lowIndex, highIndex);
			qickSort(array, lowIndex, privotIndex - 1);
			qickSort(array, privotIndex + 1, highIndex);
		}
	}
}

输出结果：

test1:

原数组：[-41, 21, -38, 71, -26, -12, -57, -25, 19, 50]
排序后的数组：[-57, -41, -38, -26, -25, -12, 19, 21, 50, 71]

test2:

原数组：[-10, 8, 7, 31, -49, 9, 30, -79, 64, 44]
排序后的数组：[-79, -49, -10, 7, 8, 9, 30, 31, 44, 64]

...

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