#include <bits/stdc++.h>
using namespace std;
int a[1000 * 100 + 10];
vector<int> v;
int main() {
  int t;
  cin >> t;
  for (int i = 0; i < t; i++) {
    int n;
    cin >> n;
    for (int j = 0; j < n; j++) cin >> a[j];
    sort(a, a + n);
    v.clear();
    for (int j = 0; j < ((n + 1) / 2); j++) {
      if (j == n - j - 1)
        v.push_back(a[j]);
      else {
        v.push_back(a[j]);
        v.push_back(a[n - j - 1]);
      }
    }
    for (int j = v.size() - 1; j > 0; j--) cout << v[j] << ' ';
    cout << v[0] << endl;
  }
  return 0;
}
