题解 | #高精度整数加法#

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.hasNext()) { // 注意 while 处理多个 case
            String a = in.next();
            String b = in.next();
            if(a.length()<b.length()){
                String temp = b;
                b=a;
                a=temp;
            }
            int bLength = b.length()-1;
            int jw = 0;
            StringBuilder  result = new StringBuilder ();
            for(int i=a.length()-1; i>=0; i--){
                int sumSub = Integer.parseInt(a.substring(i,i+1));
                if(bLength>=0){
                    sumSub = sumSub +Integer.parseInt(b.substring(bLength,bLength+1))+jw;
                }else{
                    sumSub = sumSub+jw;
                }
                jw = sumSub>=10?1:0;
			  //是否为长数字最左一位，若是最左一位且存在进位
                if(i==0&&jw==1){
                    result.append(sumSub%10);
                    result.append(sumSub/10);
                }else{
                    result.append(sumSub%10);
                }
                bLength = bLength-1;
            }
            System.out.println(result.reverse().toString());
        }
    }
}