蓝桥杯:排列序数(火星人) Java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.linkedList;
import java.util.List;
import java.util.Scanner;
// 1:无需package
// 2: 类名必须Main, 不可修改

public class Main {
    static char[] ch;
    static int n;
    static String s;
    static boolean[] bo;
    static linkedList link;
    static List> res=new ArrayList<>();
    
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        n=scan.nextInt();
        int num=scan.nextInt();//人类要加上的数
        s=new String();
        for (int i = 0; i < n; i++) {
            //注意是+=,不是=(如果是=,则只取最后一个数)
            s+=scan.nextInt()+"";
        }
        ch=s.toCharArray();        
        Arrays.sort(ch);
        
        bo=new boolean[n+2];
        link=new linkedList<>();
        dfs(0);
        
        for (int i = 0; i < res.size(); i++) {
            String st=new String();
            // System.out.println(res.get(i));
            for(int j=0;j(link));
            return;
        }

        for (int i = 0; i < n; i++) {
            if(bo[i]==true){
                continue;
            }else{
                //将ch[i]转化为数字
                link.addLast(ch[i]-'0');
                bo[i]=true;
                dfs(k+1);
                link.removeLast();//回溯!
                bo[i]=false;
            }
        }
        
    }
}