这是100分的代码

#include<iostream>
#include<iomanip>
using namespace std;

int main()
{
	int n, k;
	cin >> n >> k;
	double sumA = 0, sumB = 0, numA = 0, numB = 0;

	for (int i = 1; i <= n; i++)
	{
		if (i % k == 0)
		{
			sumA += i;
			numA++;
		}
		else
		{
			sumB += i;
			numB++;
		}
	}
	
	double aveA, aveB;
	aveA = sumA / numA;
	aveB = sumB / numB;

	cout <<fixed<< setprecision(1) << aveA << " " <<fixed<< setprecision(1) << aveB;

	return 0;
 }

这是40分的代码

#include<iostream>
#include<iomanip>
using namespace std;

int main()
{
   int n, k;
   cin >> n >> k;
   float sumA = 0, sumB = 0, numA = 0, numB = 0;//按道理用float和double区别应该不大的，但不知道为什么只有40分

   for (int i = 1; i <= n; i++)
   {
   	if (i % k == 0)
   	{
   		sumA += i;
   		numA++;
   	}
   	else
   	{
   		sumB += i;
   		numB++;
   	}
   }
   
   float aveA, aveB;//还有这里
   aveA = sumA / numA;
   aveB = sumB / numB;

   cout <<fixed<< setprecision(1) << aveA << " " <<fixed<< setprecision(1) << aveB;

   return 0;
}