E题代码：
#include<stdio.h>
int main(void)
{
int m,n,i,j,flag;
double item,sum;
j=1;
scanf("%d\n",&m);
while(j<=m){
scanf("%d",&n);
flag=1;
sum=0;
for(i=1;i<=n;i++){
item=flag*1.0/i;
sum=sum+item;
flag=-flag;
}
printf("%.4f\n",sum);
j++;
}
return 0;
}