题解 | #高精度整数加法#10进制

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String a = in.nextLine();
            String b = in.nextLine();
            int aIndex = a.length() - 1;
            int bIndex = b.length() - 1;
            String res = "";
            int carry = 0;
            while (true) {
                if (aIndex < 0 && bIndex < 0) {
                    if (carry > 0) {
                        res = carry + res;
                    }
                    break;
                }
                int aa = 0;
                if (aIndex >= 0) {
                    aa =  a.charAt(aIndex) - '0';
                }
                int bb = 0;
                if (bIndex >= 0) {
                    bb = b.charAt(bIndex) - '0';
                }
                int sum = aa + bb + carry;
                res = (sum % 10) + res;
                carry = sum / 10;
                aIndex--;
                bIndex--;

            }
            System.out.println(res);
        }
    }
}