#include <bits/stdc++.h>
using namespace std;
long long t, n, v[200001], sol[200001];
void solve() {
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> v[i];
  sort(v + 1, v + n + 1);
  long long st = n / 2 + n % 2;
  long long dr = n / 2 + 1 + n % 2;
  while (st > 0 || dr <= n) {
    if (st > 0) {
      cout << v[st] << " ";
      st--;
    }
    if (dr <= n) {
      cout << v[dr] << " ";
      dr++;
    }
  }
  cout << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> t;
  while (t--) solve();
  return 0;
}
