HDU ACM 11 2011 多项式求和

#include <iostream>
using namespace std;
int main()
{
int m, n, i;
double sum;
cin >> m;
while (m--)
{
cin >> n;
sum = 0;
for ( i = 1; i <= n; i++)
{
if (i%2 == 0)
{
sum = sum - double(1.0/i);
}
else if (i%2 != 0)
{
sum = sum + double(1.0/i);
}
}
cout << fixed;
cout.precision(2);
cout << sum << endl;
}
return 0;
}