Envío 3356

Código

import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        String number = sn.nextLine();
        String number2 = sn.nextLine();
        List<Integer> longNumber = new ArrayList<>();
        List<Integer> longNumber2 = new ArrayList<>();
        for (int i = 0; i < number.length(); i++) {
            longNumber.add(Integer.parseInt(Character.toString(number.charAt(i))));
        }
        for (int i = 0; i < number2.length(); i++) {
            longNumber2.add(Integer.parseInt(Character.toString(number2.charAt(i))));
        }
        long index = longNumber.size();
        int carry = 0;
        List<Integer> upTo = longNumber2.size() > index ? longNumber2 : longNumber;
        Collections.reverse(longNumber);
        Collections.reverse(longNumber2);
        List<Integer> answer = new ArrayList<>();
        for (int i = 0; i < upTo.size(); i++) {
            int current = carry;
            if (i < longNumber.size()) {
                current += longNumber.get(i);
            }
            if (i < longNumber2.size()) {
                current += longNumber2.get(i);
            }
            answer.add(current % 10);
            carry = Math.round(current / 10);
        }

        if (carry > 0) {
            answer.add( 1);
        }
        Collections.reverse(answer);
        answer.forEach((a) -> System.out.print(a));
    }

}