标签：its include div scanf pre bsp main double clu
题解：
答案就是n*(n+1)/2/(2*n-1)
代码：
#include<bits/stdc++.h> double n; int main() { scanf("%lf",&n); printf("%.9lf",n*(n+1)/2/(2*n-1)); }
标签：its include div scanf pre bsp main double clu
原文地址：http://www.cnblogs.com/xuanyiming/p/7747178.html
