题解 | #牛牛学数列3#
牛牛学数列3
https://www.nowcoder.com/practice/f65c726d081c4160a9356eabf0dc21d9
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#刷题#
#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
int n,sum=0,flag=1;
double sum1=0;
cin>>n;
for(int i=1;i<=n;i++)
{
sum+=(2*i-1)*flag;
flag*=-1;
sum1 +=1.00/sum;
}
cout<<fixed<<setprecision(3)<<sum1<<endl;
return 0;
}
#刷题#
