#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;
}
