快速排序

package com.gem.JavaHomeworkDay5;public class QuickSort {public static void main(String[] args) {int[] arr = new int[20];for (int i = 0; i < arr.length; i++) {arr[i] = (int)(Math.random() * 100);System.out.print(arr[i] + " ");}System.out.println();quickSort(arr,0,arr.length - 1);for (int i : arr) {System.out.print(i + " ");}}public static int divideArr(int[] arr,int start,int end){ //每次都以最左边的元素作为基准值 int base = arr[start]; //start一旦等于end，就说明左右两个指针合并到了同一位置，可以结束此轮循环。while(start < end){while(start < end && base <= arr[end]){end--;}//右边的数小于基准值时，和基准值换位if(start < end){int temp = arr[end];arr[end] = arr[start];arr[start] = temp;start++;}//从右边开始向左循环，直到基准值小于左边的，换位while(start < end && arr[start] <= base){start++;}if(start < end){int temp = arr[end];arr[end] = arr[start];arr[start] = temp;end--;}}return end;}public static void quickSort(int[] arr,int start,int end){if(start > end){return;}else{int position = divideArr(arr,start,end);quickSort(arr,start,position - 1);quickSort(arr,position + 1,end);}}}