快速排序实现

1.结束条件: low = high

2.快速排序要分而治之。故需要分的位置，位置便是当前元素经过排列后应该所在的位置。

3.对于单次的排列，都使得一个元素排在了正确的位置，她的左面比她小，右侧比她大。

package com.jue.quicksort;

public class Quicksort {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int data[] = { 8, 3, 7, 1, 5, 6, 4, 9, 2 };
		logs("old : ", data);
		quickSort(data, 0, data.length - 1);
		logs("new : ", data);
	}

	static void logs(String str, int[] data) {
		StringBuffer sb = new StringBuffer(str);
		for (int value : data) {
			sb.append(value + " ");
		}
		System.out.println(sb);
	}

	public static void quickSort(int[] data, int low, int high) {
		if (low >= high) {
			return;
		}

		int index = getSortedIndex(data, low, high);
		quickSort(data, low, index - 1);
		quickSort(data, index + 1, high);
	}

	private static int getSortedIndex(int[] data, int low, int high) {
		int currentData = data[low];
		int currentDataIndex = low;
		while (low < high) {

			if (currentDataIndex == low) {
				if (currentData > data[high]) {
					data[low] = data[high];
					data[high] = currentData;
					currentDataIndex = high;
					low++;
				} else if (currentData <= data[high]) {
					high--;
				}
			} else if (currentDataIndex == high) {// move to left

				if (currentData < data[low]) {//
					data[high] = data[low];
					data[low] = currentData;
					currentDataIndex = low;
					high--;
				} else if (currentData >= data[low]) {
					low++;
				}
			}
		}
		return currentDataIndex;
	}

}

输出的结果