#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cctype>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
const int mx=1010;
int a[mx],b[mx],c[mx];
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n,i,j;
        cin>>n;
        double avger,sum,win=0;
        sum=n*(n-1);
        for(i=1;i<=n;i++){
            cin>>a[i];
        }
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                if(i!=j&&a[i]>a[j])
                    win++;
            }
        }
        avger=win/sum;
        printf("%.6lf\n",avger);
    }
    return 0;
}