1001 A+B Format

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

#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstring>
#include <climits>
#include <iostream>
#include <algorithm>
#define wzf ((1 + sqrt(5.0)) / 2.0)
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;

int a, b, sum, cnt;

stack <char> s;

int main()
{
    scanf("%d%d", &a, &b);
    sum = a + b, cnt = 0;
    if (sum < 0)
    {
        printf("-");
        sum = abs(sum);
        while (sum)
        {
            cnt ++;
            s.push('0' + sum % 10);
            sum /= 10;
            if (sum != 0 && cnt % 3 == 0)
                s.push(',');
        }
        while (s.size())
        {
            printf("%c", s.top());
            s.pop();
        }
        printf("
");
    }
    else if (sum > 0)
    {
        while (sum)
        {
            cnt ++;
            s.push('0' + sum % 10);
            sum /= 10;
            if (sum != 0 && cnt % 3 == 0)
                s.push(',');
        }
        while (s.size())
        {
            printf("%c", s.top());
            s.pop();
        }
        printf("
");
    }
    else
        printf("0
");
    return 0;
}