1 public class QuickSort {
2 Random rand = new Random();
3 public int[] quickSort(int[] array) {
4 if (array == null || array.length = 0) {
5 return array;
6 }
7 quickSort(int[] array,0, array.length -1)
8 return array;
9 }
10 private void quickSort(int[] array, int left, int right) {
11 if (left >= right){
12 return;
13 }
14 int pivot = partition(array, left, right);
15 quickSort(array, left, pivot - 1);
16 quickSort(array, pivot + 1, right);
17 }
18 private void partition(int[] array, int left, int right){
19 int pivotIndex = left + rand.nextInt(right - left)/2;
20 int pivot = array[pivotIndex];
21 swap(array, pivot, pivotIndex);
22 int leftIndex = left;
23 int rightIndex = right -1;
24 while (leftIndex >= rightIndex){
25 if (array[leftIndex] < pivot){
26 leftIndex++;
27 } else if (array[rightIndex] > pivot){
28 rightIndex--;
29 } else {
30 swap(array, leftIndex, rightIndex);
31 }
32 }
33 sawap(array, leftIndex, pivot);
34 return leftIndex;
35 }
36
37 private void swap(int[] array, int left, int right){
38 int temp = array[left];
39 array[left] = array[right];
40 array[right] = temp;
41 }
42 }
43
44
