백준: 소금폭탄

내 코드

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String now = scan.nextLine();
        String target = scan.nextLine();

        int[] aNow = makeIntArr(now);
        int[] aTarget = makeIntArr(target);

        String result = "";
        for (int i = 2; i >= 0; i--) {
            int sleep = aTarget[i] - aNow[i];
            if (sleep < 0) {
                if (i > 0) {
                    aTarget[i - 1]--;
                    sleep = 60 + sleep;
                } else {
                    sleep = 24 + sleep;
                }
            }
            result = String.format(":%02d%s", sleep, result);
        }
        result = ":00:00:00".equals(result) ? ":24:00:00" : result;
        System.out.println(result.substring(1));
    }
    
    private static int[] makeIntArr(String ss) {
        int idx = 0;
        int[] arr = new int[3];
        for (String s: ss.split(":"))
            arr[idx++] = Integer.parseInt(s);
        return arr;
    }
}