题解 | #高精度整数加法#

import java.util.*;

// 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();
            int len = Math.max(a.length(), b.length());
            int alen = a.length();
            int blen = b.length();
            char [] arr = new char[len];
            int num = 0; 
            for (int i = 1 ; i <= len ; i++ ) {
                char ac = '0';
                char bc = '0';
                if (alen >= i) {
                    ac = a.charAt(alen - i);
                }
                if (blen >= i) {
                    bc = b.charAt(blen - i);
                }
                int anum =  (int)( ac -'0');
                int bnum =  (int) (bc -'0');
                int res = anum + bnum + num;
                if (res >= 10  ) {
                    num = 1 ;
                    arr[len - i] = (char)(res % 10 +'0');
                } else {
                    num = 0 ;
                    arr[len - i] =  (char)(res +'0');
                }
            }
            StringBuffer sbuffer = new StringBuffer();
            String  re = String.valueOf(arr);
            if  (num==1){
                 sbuffer.append("1");
            }
            sbuffer.append(re);
            System.out.println(sbuffer);
        }
    }
}