Envío 6484

Código

import java.util.*;
import java.lang.*;
import java.io.*;

class Main {

    public static void main(String[] args) throws java.lang.Exception {
        Scanner sc = new Scanner(System.in);

        String number = sc.nextLine();
        String v[] = number.split("");
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = v.length-1; i >=0; i--) {
            list.add(Integer.parseInt(v[i]));
        }
        
        String number2 = sc.nextLine();
        String v2[] = number2.split("");
        ArrayList<Integer> list2 = new ArrayList<>();
        for (int i = v2.length-1; i >=0; i--) {
            list2.add(Integer.parseInt(v2[i]));
        }
        System.out.println(sumNumbers(list,list2));
    }

    public static String sumNumbers(ArrayList<Integer> listOne, ArrayList<Integer> listTwo) {
    	ArrayList<Integer> list = new ArrayList<>();
    //	int minSize = (listOne.size() <= (listTwo.size() ) ? listOne.size() : listTwo.size();
        int carry =0;        
        for (int i = 0; i < listOne.size() && i < listTwo.size(); i++) {
        	int val1= listOne.get(i)==null ? 0 : listOne.get(i);
        	int val2= listTwo.get(i)==null ? 0 : listTwo.get(i);
            int sum = val1 + val2 + carry;
            list.add(sum%10);
            carry=sum/10;
        }
        
        if(carry!=0) list.add(carry);
        
        Collections.reverse(list);
        return listToString(list);
    }

    public static String listToString(ArrayList<Integer> list) {
        StringBuilder st =  new StringBuilder();
        for (int numb : list) {
            st.append(numb);
        }
        return st.toString();
    }
}