Solution.java

import java.util.*;

class Solution {
    public String solution(int[] numbers) {
        String answer = "";
        
        String[] number = new String[numbers.length];
        
        for (int i = 0; i < numbers.length; i++) {
            number[i] = String.valueOf(numbers[i]);
        }
        
        Arrays.sort(number, new MyComparator());
        
        for (String n : number) {
            answer += n;
        }
        
        if (answer.charAt(0) == '0') answer = "0";
        
        return answer;
    }
}

class MyComparator implements Comparator<String> {
    public int compare(String s1, String s2) {
        return (s2 + s1).compareTo(s1 + s2);
    }
}