#include <bits/stdc++.h>
clock_t time_p = clock();
using namespace std;
const int N = 1e5 + 10, mod = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int tc;
  cin >> tc;
  while (tc--) {
    int n;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) cin >> a[i];
    sort(a, a + n);
    int res[n];
    for (int i = 0, j = 0, k = n - 1; i < n;) {
      if (k == j) {
        res[i] = a[j];
        break;
      }
      res[i++] = a[k--];
      res[i++] = a[j++];
    }
    for (int i = n - 1; i >= 0; i--) cout << res[i] << " ";
    cout << "\n";
  }
  return 0;
}
