#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, ar[100009];
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> ar[i];
    sort(ar + 1, ar + n + 1);
    int i, j;
    i = n / 2;
    j = i + 1;
    while (i) {
      cout << ar[j] << " " << ar[i] << " ";
      i--;
      j++;
    }
    if (n % 2 == 1) {
      cout << ar[n];
    }
    cout << endl;
  }
}
