AC程式碼：

#include <iostream>
#include <cstdio>
int main(void)
{
    freopen("in.txt","r",stdin);
    int m;
    scanf("%d",&m);
    while(m--)
    {
        int n;
        scanf("%d",&n);
        double sum = 0,t=1,x;
        int k=1;
        for(int i=1;i<=n;i++)
        {
            x
 
=1/t;
            x=k*x;
            sum+=x;
            t++;
            k=(-1)*k;
        }
        printf("%.2lf\n",sum);
    }
    
    
    fclose(stdin);
    return 0;
}