Envío 6483

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 = 0; i < number.length(); i++) {
            list.add(Integer.parseInt(v[i]));
        }
        int digit = sc.nextInt();
        System.out.println(sumOne(list,digit));
    }

    public static String sumOne(ArrayList<Integer> list, int digit) {
            int carry =0;        
        for (int i = list.size()-1; i >= 0; i--) {
            int sum = list.get(i)+ digit+carry;
            list.set(i,sum%10);
            carry=sum/10;
            digit=0;
            if(carry==0) return listToString(list, carry);
        }
        
        return listToString(list, carry);
    }

    public static String listToString(ArrayList<Integer> list, int carry) {
        StringBuilder st =  new StringBuilder();
        if(carry!=0)  st.append(carry);
        for (int numb : list) {
            st.append(numb);
        }
        return st.toString();
    }
}