hdu-2011-多项式求和

#include<stdio.h>

int main()

{
int s;
scanf("%d",&s);
while(s--)
{
int n,i;
double sum=0.0;
scanf("%d",&n);
for(i=1;i<=n;i++)
{
if(i%2==0)
sum-=1.0/i;
else
sum+=1.0/i;
}
printf("%.2lf\n",sum);
}
return 0;

}