= 多项式求和 =
http://acm.hdu.edu.cn/showproblem.php?pid=2011
{{{#!cplusplus
#include "stdio.h"
void main()
{
	int m,i,n;
	float sum;
	scanf("%d",&m);
	for(i=0;i<m;i++)
	{
		sum=0;
		scanf("%d",&n);
	
		while(n>0)
		{
			if(n%2==1)
				sum+=1/(double)n;
			else 
				sum-=1/(double)n;
			n--;		
		}
		printf("%.2f\n",sum);
	}



}
}}}