堆排序---Java算法

如果代码有不理解的地方大家可看这个老师的视频，只不过他是c语言写的。

https://www.bilibili.com/video/BV1fp4y1D7cj/?spm_id_from=333.337.search-card.all.click&vd_source=49693d68f3b5f08a9c6550178d174d6ehttps://www.bilibili.com/video/BV1fp4y1D7cj/?spm_id_from=333.337.search-card.all.click&vd_source=49693d68f3b5f08a9c6550178d174d6e 

代码

/**
 * @description: TODO
 * @author 48zj
 * @date 2023/4/16 20:58
 * @version 1.0
 */

import java.util.Arrays;

/**
 *@BelongsProject: javaSenior
 *@BelongsPackage: PACKAGE_NAME
 *@Author: 48-zj
 *@CreateTime: 2023-04-16  20:58
 *@Description: TODO
 *@Version: 1.0
 */
public class Duisort {

    public static void swap(int a ,int b,int arr[]){
        int temp=0;
        temp =arr[a];
        arr[a]=arr[b];
        arr[b]=temp;
    }
    /**
     * @Author 04-48-zj
     * @Description //TODO
     * @Date 21:28 2023/4/16
     * @Param
     * @param: arr 数组
     * @param: n 数组长度
     * @param: i
     * @return void
     **/
    public  static  void heapify(int arr[], int n, int i){
        int largest =i;
        int lson =i*2+1;
        int rson =i*2+2;
        if(lson<n && arr[largest]<arr[lson])
            largest=lson;
        if(rson < n && arr[largest]< arr[rson]){
            largest=rson;
        }
        if(largest != i){
            swap(largest,i,arr);
            heapify(arr,n,largest);
        }
    }
//堆排序入口
  public static void heap_sort(int arr[],int n){
        int i;
        //建堆
      for(i=n/2-1;i>=0;i--){
          heapify(arr,n,i);
      }
      //排序
      for(i= n-1;i>0;i--){
          swap(i,0,arr);
          heapify(arr,i,0);
      }
  }

    public static void main(String[] args) {
        int arr[] = {3,2,4,5,7,6,67,43,21,42,31};
        int n=arr.length;
        System.out.println("排序前"+Arrays.toString(arr));
        heap_sort(arr,n);
        System.out.println("排序后"+Arrays.toString(arr));
    }

}

运行结果；

D:\develop-tools\Java\jdk1.8.0_331\bin\java.exe "-javaagent:D:\develop-tools\IDear\idearj\IntelliJ IDEA 2020.3.4\lib\idea_rt.jar=53562:D:\develop-tools\IDear\idearj\IntelliJ IDEA 2020.3.4\bin" -Dfile.encoding=UTF-8 -classpath D:\develop-tools\Java\jdk1.8.0_331\jre\lib\charsets.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\deploy.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\access-bridge-64.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\cldrdata.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\dnsns.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\jaccess.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\jfxrt.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\localedata.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\nashorn.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\sunec.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\sunjce_provider.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\sunmscapi.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\sunpkcs11.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\ext\zipfs.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\javaws.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\jce.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\jfr.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\jfxswt.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\jsse.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\management-agent.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\plugin.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\resources.jar;D:\develop-tools\Java\jdk1.8.0_331\jre\lib\rt.jar;D:\JAVA文件\Ideajavaworkspace\javaSenior\out\production\day02 Duisort
排序前[3, 2, 4, 5, 7, 6, 67, 43, 21, 42, 31]
排序后[2, 3, 4, 5, 6, 7, 21, 31, 42, 43, 67]

Process finished with exit code 0