PAT-PAT (Advanced Level) Practise 1001. A+B Format (20) 【二星级】

题目链接：http://www.patest.cn/contests/pat-a-practise/1001

题面：

1001. A+B Format (20)

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

Each input file contains one test case. Each case contains a pair of integers a and b where -1000000 <= a, b <= 1000000. The numbers are separated by a space.

Output

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

题意大意：

    输出a+b，以每三位加一个逗号的格式。

解题：

    注意后面部分假设小于100需加前缀0。

代码：

#include <cstdio>
#include <vector>
#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>
using namespace std;
int main()
{
	int a,b,ans;
    cin>>a>>b;
    ans=a+b;
	if(ans<0)
	{
		cout<<"-";
		ans=-ans;
	}
	if(ans<1000)
		cout<<ans<<endl;
	else if(ans<1000000)
		cout<<ans/1000<<","<<fixed<<setw(3)<<setfill('0')<<ans%1000<<endl;
	else
		cout<<ans/1000000<<","<<fixed<<setw(3)<<setfill('0')<<ans/1000-ans/1000000*1000<<","<<fixed<<setw(3)<<setfill('0')<<ans%1000<<endl;
	return 0;
}