Java实现快速排序

快速排序

public class QuickSort { public static void quickSort(int[] arr, int l, int r) { if (arr == null || arr.length < 2) { return; } if (l < r) { swap(arr, l + (int) Math.random() * (r - l + 1), r); int[] p = partition(arr, l, r); quickSort(arr, l, p[0] - 1); quickSort(arr, p[1] + 1, r); } } public static int[] partition(int[] arr, int l, int r) { int less = l - 1; int more = r; while (l < more) { if (arr[l] < arr[r]) { swap(arr, ++less, l++); } else if (arr[l] > arr[r]) { swap(arr, --more, l); } else { l++; } } swap(arr, more, r); return new int[] { less + 1, more }; } public static void swap(int[] arr, int i, int j) { int tmp; tmp = arr[i]; arr[i] = arr[j]; arr[j] = tmp; } public static void main(String[] args) { int[] arr = { 2, 3, 6, 1, 8, 5, 5, 6, 0 }; quickSort(arr, 0, arr.length - 1); for (int i = 0; i < arr.length; i++) { System.out.println(arr[i]); } } }