#include <bits/stdc++.h>
using namespace std;
int a[100010];
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i];
    sort(a, a + n);
    int i = (n - 1) / 2, j = i + 1;
    while (i >= 0 || j <= n - 1) {
      if (i >= 0) cout << a[i--] << " ";
      if (j <= n - 1) cout << a[j++] << " ";
    }
    cout << endl;
  }
  return 0;
}
