1001 A+B Format （20 分）

1001 A+B Format （20 分）

Calculate a+b and output the sum in standard format -- that is, the digits must be separated into groups of three by commas (unless there are less than four digits).

Input Specification:

Each input file contains one test case. Each case contains a pair of integers a and b where −10​^6​​≤a,b≤10^​6​​. The numbers are separated by a space.

Output Specification:

For each test case, you should output the sum of a and b in one line. The sum must be written in the standard format.

Sample Input:

-1000000 9

Sample Output:

-999,991

分析：注意到a,b的范围可以用int型表示，int可以表示10^9的范围，一开始想复杂了，其实直接把字符串逆置后，从高位输出，每输出3个数字输出一个逗号就行了。

 /**
 * Copyright(c)
 * All rights reserved.
 * Author : Mered1th
 * Date : 2019-02-24-19.21.16
 * Description : A1001
 */
 #include<cstdio>
 #include<cstring>
 #include<iostream>
 #include<cmath>
 #include<algorithm>
 #include<string>
 #include<unordered_set>
 #include<map>
 #include<vector>
 #include<set>
 using namespace std;

 int main(){
 #ifdef ONLINE_JUDGE
 #else
     freopen("1.txt", "r", stdin);
 #endif
     int a,b,c;
     scanf("%d%d",&a,&b);
     c=a+b;
     ){
         printf("-");
         c=-c;
     }
     string s=to_string(c);
     reverse(s.begin(),s.end());
     int len=s.length();
     ;i>=;i--){
         )%==&&i!=len-&&i>){
             printf(",");
         }
         printf("%c",s[i]);
     }
     ;
 }