[백준][Java] 10610번 30 (문자열)

3의 배수에 해당하는 숫자들의 규칙만 알면 쉬움 (걍 수학임 이 문제는)

내림차순

 

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Arrays;
 
public class Main {
 
    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    private static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
 
    public static void main(String[] args) throws IOException {
        char[] arr = br.readLine().toCharArray();
        Arrays.sort(arr);
        
        if(arr[0]!='0') {
            System.out.println("-1");
            return;
        }
        int total = 0;
        StringBuilder sBuilder = new StringBuilder();
        for(int i=arr.length-1; i>=0; i--) {
            total += (arr[i]-'0');
            sBuilder.append(arr[i]-'0');
        }
        if(total%3!=0) {
            System.out.println("-1");
            return;
        }
        
        System.out.println(sBuilder.toString());
        
        
        
//        bw.write("");
//        bw.flush();
//        bw.close();
 
    }
 
 
    
//    private static int stoi(String input) {
//        return Integer.parseInt(input);
//    }
    
}