[codeforces 1293B] JOE is on TV! 1+1/2+1/3+1/4+......+1/n序列

[codeforces 1293B] JOE is on TV!    1+1/2+1/3+1/4+......+1/n序列

总目录详见https://blog.csdn.net/mrcrack/article/details/103564004

在线测评地址https://codeforces.com/contest/1293/problem/B

Problem	Lang	Verdict	Time	Memory
B - JOE is on TV!	GNU C++11	Accepted	31 ms	0 KB

//没想到如此简单，提交那一刻还不敢相信，不过证明过程大致如下
//因2/n<1/n+1/(n-1)，故让分子为1,分母为n,n-1,n-2,......

#include <stdio.h>
int main(){
	int n,i;
	double ans=0;
	scanf("%d",&n);
	for(i=n;i>=1;i--)ans+=1.0/i;
	printf("%.12lf\n",ans);
	return 0;
}