Fully ranked two (java)

Full arrangement idea 2:
If {a, b, c} 's full arrangement result is {a, b, c}, {a, c, b} {b, a, c} {b, c, a} {c, b, a} {c, a, b}. It can be seen that we change the first bit of the character array in turn, and the remaining two bits can be solved recursively, but each time a situation is solved, it will disrupt its original order, so we need to go back and return to its original Some states.

code show as below:

import java.util.ArrayList;
import java.util.Scanner;
public class Qpal {
    //全排列法二（多支路递归回溯）
    ArrayList<String> news=new ArrayList<>();//需要将Arraylist建立为全局变量
    public ArrayList<String> qpl1(String a)
    {
        char []b=a.toCharArray();//转为字符数组方便各个交换
        ArrayList<String> news1=qpl(b,0);
        return news1;
    }
    static void swap(char []a,int b,int c)//交换数组中的两个值
    {
        char temp=a[c];
        a[c]=a[b];
        a[b]=temp;
    }
    private ArrayList<String> qpl(char []a, int b)
    {

        if(b==a.length)//递归出口
        {
            news.add(new String(a));
        }
        for (int i=b;i<=a.length-1;i++)
    {
        swap(a,b,i);//交换第一位元素
        qpl(a,b+1);
        swap(a,b,i);//回溯
    }
        return news;
    }
    public static void main(String[] args) {
        Scanner a=new Scanner(System.in);
        String b=a.nextLine();//字符串输入
        ArrayList<String> news=new Qpal().qpl1(b);
        System.out.println(news);
    }
}

The results are as follows: