#include <bits/stdc++.h>   using namespace std;   using ll = long long;   using pii = pair<ll, ll>;   const ll MOD = 1e9 + 7, N = 1e5 + 10;   void test() {     ll n;     cin >> n;     vector<ll> a(n);     for (ll i = 0; i < n; i++) {       cin >> a[i];     }     vector<ll> ans;     sort(a.begin(), a.end());     ll l = 0, h = n - 1;     while (l < h) {       ans.push_back(a[l]);       ans.push_back(a[h]);       l++, h--;     }     if (l == h) ans.push_back(a[l]);     reverse(ans.begin(), ans.end());     for (ll i = 0; i < n; i++) {       cout << ans[i] <<    n [i == n - 1];     }     return;   }   int32_t main() {     ios::sync_with_stdio(false);     cin.tie(NULL);     ll tt = 1;     cin >> tt;     for (ll i = 0; i < tt; i++) test();     return 0;   }   