파이썬

def solution(n):
    answer = ''.join(sorted(str(n),reverse = True))
    return int(answer)

자바

import java.util.*;
class Solution {
    public long solution(long n) { 
        String[] list = String.valueOf(n).split(""); 
        Arrays.sort(list);
        StringBuffer sb = new StringBuffer();
        for(String s: list){sb.append(s);} 
        return Long.parseLong(sb.reverse().toString());
    }
}

자바 collect 아직 좀 느림

import java.util.*;

class Solution {
    public long solution(long n) {
        return Long.parseLong(String.valueOf(n).chars().mapToObj(ch -> (char) ch)
                .sorted(Comparator.reverseOrder())
                .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
                .toString());
    }
}