#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  for (int i = 0; i < t; i++) {
    int n;
    cin >> n;
    int a[n];
    for (int j = 0; j < n; j++) {
      cin >> a[j];
    }
    sort(a, a + n);
    int b[n];
    int u = 0;
    for (int p = 0; p < n; p++) {
      b[n - 1 - p] = a[u];
      if (p % 2 == 0) {
        u = u + n - 1 - p;
      } else {
        u = u - (n - 1 - p);
      }
    }
    for (int ju = 0; ju < n; ju++) {
      cout << b[ju] << "\n";
    }
  }
  return 0;
}
