#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl "\n"
const int MAXN = 16000 + 5;
const ll MOD = 1e9 + 7;
const string hexS = "0123456789ABCDEF";

int main(){
    ios::sync_with_stdio(false);
    int t;
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        vector<ll> ve;
        for(int i = 1; i <= n * 2; i++) {
            ll k;
            cin >> k;
            ve.push_back(k);
        }
        sort(ve.begin(), ve.end());
        int l = 0, r = n * 2 - 1;
        int now = 0;
        while(l <= r) {
            if(now != 0) cout << " ";
            if(now % 2) {
                cout << ve[l];
                l++;
            } else {
                cout << ve[r];
                r--;
            }
            now++;
        }
        cout << endl;
    }

    return 0;
}