【一只蒟蒻的刷题历程】 【PAT (Advanced Level) Practice】 1001 A + B格式

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

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题目大意：

计算a + b并以标准格式输出总和-也就是说，必须用逗号将数字分成三组（除非少于四位）。

输入规格：

每个输入文件包含一个测试用例。 每种情况都包含一对整数a和b，其中-10‐6‐≤a，b≤10‐6。 这些数字用空格分隔。

输出规格：

对于每个测试用例，应在一行中输出a和b的总和。 总和必须以标准格式书写。

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代码：

#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <set>
using namespace std;
int main() 
{
    int a,b;
    string ans;
    cin>>a>>b;
	int c=a+b;
	if(c==0)
	{
		cout<<c;
		return 0;
	}
	if(c<0) cout<<"-";
	c = abs(c); 
	while(c)  //把c转为字符串ans
	{
		ans+=c%10+'0';
		c/=10;
	}
	for(int i=ans.size()-1;i>=0;i--) //倒着输出
	{
		cout<<ans[i];
		if(i%3==0 && i!=0)
		cout<<",";
	}
    return 0;
}