java算法----排序----（4）快速排序

 package log;

 public class Test4 {

     /**
      * java算法---快速排序
      *
      * @param args
      */
     public static void main(String[] args) {
         // 需要排序的数组
         int arr[] = { 49, 20, 36, 51, 18, 94, 61, 31, 50 };
         // 循环输出该数组内容
         System.out.println("排序之前：");
         for (int a : arr) {
             System.out.print(a + "\t");
         }
         System.out.println();

         if (arr.length > 0) {
             sort(arr, 0, arr.length - 1);
         }
         // 循环输出该数组内容
         System.out.println("排序之后：");
         for (int a : arr) {
             System.out.print(a + "\t");
         }
         System.out.println();

     }

     public static int getMiddle(int[] list, int low, int high) {
         int temp = list[low];
         while (low < high) {
             while (low < high && list[high] >= temp) {
                 high--;
             }
             list[low] = list[high];
             while (low < high && list[low] <= temp) {
                 low++;
             }
             list[high] = list[low];
         }
         list[low] = temp;
         return low;
     }

     public static void sort(int[] list, int low, int high) {
         if (low < high) {
             int middle = getMiddle(list, low, high);
             sort(list, low, middle - 1);
             sort(list, middle + 1, high);
         }
     }

 }

下面这事控制台的输出