快速排序（Java随机位置快排实现）

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package cn.edu.nwsuaf.cie.qhs;

import java.util.Random;
import java.util.Scanner;

//
public class QuickSort {
   private intinitArray[];

   public int[]getInitArray() {
      return initArray;
   }

   public voidsetInitArray(int[] initArray) {
      this.initArray = initArray;
   }

   publicQuickSort() {
      // TODO Auto-generated constructor stub
   }

   publicQuickSort(int[] array) {
      this.initArray = array;
   }

   public voidrandom_partion(int start, int length) {//核心代码（随机位置二分排序）
      if (length <= 1)
         return;
      Random rand = new Random();
      int index = rand.nextInt(length) + start;
      int i = start - 1;
      int j = start;
      //System.out.println("start--->"+start+"length--->"+length+"i--->"+i+"j--->"+j+"index--->"+index+"start+length-1--->"+(start+length-1));
      this.swap(index, start + length - 1);
      for (j = start; j < start +length; j++) {
         if (initArray[j] < initArray[start+ length - 1]) {
            this.swap(++i, j);
         }
      }
      this.swap(++i, start + length - 1);
      random_partion(start, i - start + 1);
      random_partion(i + 1, length + start - i -1);
   }

   public int[]quickSorted() {
      this.random_partion(0, initArray.length);
      return initArray;
   }

   public voidswap(int a, int b) {
      int temp = initArray[a];
      initArray[a] = initArray[b];
      initArray[b] = temp;
   }

   publicstatic void main(String[] args) {
      // int[] array = { 12012, 3, 945, 965, 66, 232,65, 7, 8, 898, 56, 878,
      // 170, 13, 5 };
      QuickSort sort = new QuickSort();

      int[] array;
      int length;

      Scanner scanner = new Scanner(System.in);

      System.out.println("请输入数组长度：");
      length = scanner.nextInt();
      array = new int[length];
      for (int i = 0; i < length; i++){
         System.out.println("请输入第" + (i + 1) +"个数：");
         array[i] = scanner.nextInt();
      }

      sort.setInitArray(array);
      array = sort.quickSorted();
      for (int i = 0; i < array.length;i++) {
         System.out.println("array[" + i + "]= " +array[i]);
      }
   }
}