Envío 4497

Código

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		String inputX = sc.nextLine();
		StringBuilder X = new StringBuilder();
		X.append(inputX);
		X.reverse();
		
		String inputY = sc.nextLine();
		StringBuilder Y = new StringBuilder();
		Y.append(inputY);
		Y.reverse();
		
		int sizeX = inputX.length();
		int sizeY= inputY.length();
		StringBuilder XY = new StringBuilder();
		if (sizeX > sizeY) {
			XY.append(inputX);
		} else {
			XY.append(inputY);
		}
		
		int position = 0;
		int subintX = 0;
		int subintY = 0;
		int sumXY = 0;
		int sizeXY = XY.length();
		do {
			if (position < sizeX && position < sizeY) {
				subintX = Integer.parseInt(X.substring(position, position + 1));
				subintY = Integer.parseInt(Y.substring(position, position + 1));
				if (sumXY > 9) {
					sumXY = subintX + subintY + 1;
				} else {
					sumXY = subintX + subintY;
				}
				XY.replace(position, position + 1, Integer.toString(sumXY % 10));
			} else if (position < sizeX && sumXY > 9) {
				sumXY = Integer.parseInt(X.substring(position, position + 1));
				sumXY++;
				XY.replace(position, position + 1, Integer.toString(sumXY % 10));
			} else if (position < sizeY && sumXY > 9) {
				sumXY = Integer.parseInt(Y.substring(position, position + 1));
				sumXY++;
				XY.replace(position, position + 1, Integer.toString(sumXY % 10));
			} 
			position++;
		} while (position < sizeXY);
		
		if (sumXY > 9){
			XY.append(1);
		}

		sc.close();
		System.out.println(XY.reverse());
	}
}