PTA (Advanced Level)1001.A+B Format

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 −106≤a,b≤106. 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

思路

• 将数字转换为字符串，每隔3个输出一个,，要注意的点写在代码注释里了

代码

#include<bits/stdc++.h>
using namespace std;

int main()
{
	int a,b;
	cin >> a >> b;
	int ans = a + b;
	if(ans / 1000 == 0)		//只有3位
		cout << ans;
	else
	{
		vector<char> v;
		int cnt = 0;
		int t;
		char tmp;
		if(ans < 0)
         {
        	cout << '-';
        	ans = -ans;
         }
		while(ans)
		{
			t = ans % 10;
             tmp = t + '0';
			v.push_back(tmp);
			ans /= 10;
			cnt++;
			if(cnt == 3 && ans)		//为了避免输出形如-,999,991这样的答案
			{
				v.push_back(',');
				cnt = 0;
			}
		}
		for(int i=v.size()-1;i>=0;i--)
			cout << v[i];
	}
	return 0;
}

引用

https://pintia.cn/problem-sets/994805342720868352/problems/994805528788582400