选择一个基准元素,通常选择第一个元素或者最后一个元素,通过一趟扫描，将待排序列分成两部分,
一部分比基准元素小,一部分大于等于基准元素,此时基准元素在其排好序后的正确位置,然后再用同
样的方法递归地排序划分的两部分。
Java代码实现
package Sort;
import java.util.Arrays;
/**
* Created by zdmein on 2017/9/27.
* 快排
*/
public class quickSort1 {
public static void main(String[] args) {
int[] testData = {49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};
int[] dataSorted = quickSort(testData, 0, testData.length-1);
for(int a : dataSorted) {
System.out.print(a + " ");
}
}
/**
* 快速排序
*/
private static int partition(int[] data, int low, int high) {
int key = data[low];
while(low < high) {
while(low<high && data[high]>=key) {
high--;
}
data[low] = data[high];//(此时因low=high或data[high]<key)将high下标处的数赋给low下标处的数，保证data[low]<key
while(low<high && data[low]<=key) {
low++;
}
data[high] = data[low];//(此时因low=high或data[low]>key)将low下标处的数赋给high下标处的数，保证data[high]>key
}
data[low] = key;
return low;
}
public static int[] quickSort(int[] data, int low, int high) {
if(low < high) {
int result = partition(data, low, high);
quickSort(data, low, result-1);//对low到result-1下标间数进行排序
quickSort(data, result+1, high);//对result+1到high下标间数进行排序
}
return data;
}
}
