#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  long long int n, val;
  cin >> t;
  for (int i = 0; i < t; i++) {
    cin >> n;
    vector<int> v;
    for (long long int j = 0; j < n; j++) {
      cin >> val;
      v.push_back(val);
    }
    sort(v.begin(), v.end());
    for (long long int j = ceil(n / 2.0); j > 0; j--) {
      if (n % 2 == 1) {
        if (j == ceil(n / 2.0)) {
          cout << v[j - 1] << " ";
        } else {
          cout << v[j - 1] << " " << v[n - j] << " ";
        }
      } else {
        cout << v[j - 1] << " " << v[n - j] << " ";
      }
    }
  }
  return 0;
}
