题解 | #牛牛学数列3#
牛牛学数列3
https://ac.nowcoder.com/acm/problem/22158
#include<bits/stdc++.h>//万能头文件 using namespace std;
int main() { int n,flag=0; double a=0; double sum=0; cin >> n; for(double i=1;i<=n;i++){ if(flag==0){ sum+=1.0/i; flag=1; } else{ sum-=1.0/i; flag=0; }
}
cout << fixed << setprecision(3) << sum;
}
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