PAT甲级 —— 1001 A+B Format (20分)

• 题目链接：A+B Format (20分)

• 题目描述

  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 $-10{}^6\le a,b\le 10^6$. 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

• 满分代码

  #include<iostream>
  #include<string>
  #include<algorithm>
  using namespace std;
  
  int main()
  {
        
        
  	int a,b,sum;
  	string s;
  	cin>>a>>b;
  	sum = a+b;
  	
  	s = to_string(sum);
  	int len = s.length();
  	for(int i=0;i<len;i++)
  	{
        
        
  		cout<<s[i];
  		
  		if (s[i] == '-') 
  			continue;
   		if ((i + 1) % 3 == len % 3 && i != len - 1) 
  		 	cout << ",";
  	}
  
  	return 0;
  } 
  

• 说明：这个题主要就是加逗号的位置，从右向左每3各数要加一个逗号，用模运算处理，比较简单