快速排序——Java

快排的思想想必大家都懂，前后两个指针，向中间靠拢。我这个partition函数能保证所有相同的数都被比较一次，靠拢在一起。

代码：

 

public class Main {  public static int[] partition1(int[] arr, int begin, int end, int pivotValue) {int small = begin-1;int cur = begin;int big = end+1;while(cur!=big) {if(arr[cur] < pivotValue) {swap(arr, ++small, cur++);} else if(arr[cur] > pivotValue) {swap(arr, cur, --big);} else {cur++;}}int[] range = new int[2];range[0] = small;range[1] = big;return range;}public static void quickSort(int[] array,int low, int high) {if(array == null || array.length==0) {return;}if(low>=high) {return;}int[] res = partition1(array, low, high, array[low]);quickSort(array, low, res[0]);quickSort(array, res[1], high);}public static void main(String[] args) {int[] a = {34,2,25,1,12,34,12,56,23,15,34,12,12,54,34};quickSort(a, 0, a.length-1);for(int i=0; i<a.length; i++) {System.err.print(a[i]+" ");}}private static void swap(int[] array, int low, int high) {int temp = array[low];array[low] = array[high];array[high] = temp;}}