#include <bits/stdc++.h>
#define arr(i,n) for(ll i=0;i<n;i++)
#define ARR(i,n) for(ll i=n-1;i>=0;i--)
#define f(i,a,b)  for(ll i=a;i<b;i++)
#define F(i,a,b)  for(ll i=b-1;i>=a;i--)
#define float double
#define PI 3.14159265358979323846
#define pb push_back
#define mp make_pair
#define vi vector<ll>
#define ceil(a) (ll) ceil(a)
#define floor(a) (ll) floor(a)
#define pow(a,b) (ll) pow(a,b)
#define fixed(x) cout<<fixed<<setprecision(6)<<x;
#define vpii vector< pair<ll,ll> >
#define debug(x) cout<<(#x)<<" is "<<(x)<<endl
#define dbg(x,y)  cout<<#x<<"=" <<x<<"  and  "<<#y<<"="<<y<<endl
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (a*(b/gcd(a,b)))
#define all(v) v.begin(),v.end()
#define array(a,n) arr(i,n) cout<<a[i]<<" ";
#define array2D(a,n,m) arr(i,n) {arr(j,m) cout<<a[i][j]<<" "; cout<<endl;}
#define IOS  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
typedef long long ll;
using namespace std;
const ll  mod = 1000000000 + 7;
void solve()
{
    //code start here
    ll n;
    cin>>n;
    n=2*n;
    ll a[n];
    arr(i,n) cin>>a[i];
    sort(a,a+n);
    ll start=0,end=n-1;
    arr(i,n)
    {
        if(i%2==0) {cout<<a[start]; start++;}
        else {cout<<a[end]; end--; }
        cout<<" ";
    }
    cout<<endl;
}
int main()
{
    IOS;
    int t; cin>>t;
    while(t--)  solve();
    return 0;
}