HDOJ 2011 多项式求和

/**
* 多项式求和，注意输出格式
 * Created by YangYuan on 2017/12/8.
*/
public class Problem2011
{
public static void main(String[] args)
{
DecimalFormat df = new DecimalFormat("0.00");
Scanner scanner = new Scanner(System.in);
int m = scanner.nextInt();
for (int i = 0; i < m; i++)
{
int x = scanner.nextInt();
double sum = 0;
for (int j = 1; j <= x; j++)
{
if (j % 2 != 0)
sum += 1F / j;
else
sum -= 1F / j;
}
System.out.println(df.format(sum));
}
}
}