문제

내 풀이

import java.util.*;
class Solution {
    public long solution(long n) {
        long answer = 0;
        String str = "";
        ArrayList<String> list= new ArrayList<String>();
        while(n>0){
            list.add(""+n%10);
            n=n/10;
        }
        Collections.sort(list, Collections.reverseOrder());
        for(int i = 0 ; i<list.size() ; i++){
            str += list.get(i);
        }
        answer = Long.parseLong(str);
        return answer;
    }
}

                                  ![](https://velog.velcdn.com/images/seaho/post/25be5fb5-52cf-4986-b5b0-698d86b4b2f8/image.png)