学步园

#include<iostream>
#include<vector>
#include<fstream>
using namespace std;

int main()
{
 ifstream infile("data.txt");
 ofstream outfile("result.txt");
 if(!infile)
 {
  cout<<"data.txt open failed"<<'\n';
 }
 if(!outfile)
 {
  cout<<"result.txt open failed"<<'\n';
 }

 vector<double>vec_double;
 while(!infile.eof())
 {
  int num = 0;
  infile>>num;
  vec_double.push_back(num);
 }
 double sum = 0.0;
 int size  = vec_double.size();
 for(int i =0;i<size;i++)
 {
  sum += (1/vec_double[i]);
 }

 double harmonic_mean = 1/(sum/size);

 outfile.precision(10);
 outfile<<"调和平均数为："<<fixed<<harmonic_mean<<'\n';

 outfile.close();
 infile.close();
 return 0;
}