#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, val;
    long long l, r;
    vector<int> a;
    cin >> n;
    for (int i = 0; i < n; i++) {
      cin >> val;
      a.push_back(val);
    }
    sort(a.begin(), a.end());
    l = (int)(n - 1) / 2;
    r = l + 1;
    while (l >= 0) {
      cout << a[l] << " ";
      l--;
      if (r < n) {
        cout << a[r] << " ";
        r++;
      }
    }
    cout << "\n";
  }
}
