#include <cstdio>
int main()
{
int n, m;
scanf("%d", &m);
while(m --)
{
scanf("%d", &n);
float sum = 0;
for(int i = 1; i <= n; ++ i)
{
if(i % 2 == 0) sum -= 1.0/i;
else sum += 1.0/i;
}
printf("%.2f\n", sum);
}
return 0;
}
原文：https://www.cnblogs.com/mjn1/p/11260967.html