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