#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int t;
  cin >> t;
  while (t--) {
    long long int n, i, j, k;
    cin >> n;
    long long int a[n], b[n];
    for (i = 0; i < n; i++) {
      cin >> a[i];
    }
    sort(a, a + n);
    j = 0;
    k = n - 1;
    long long int count = 0;
    for (i = n - 1; count < n; i--) {
      if (count % 2 == 0) {
        b[i] = a[j];
        j++;
      } else {
        b[i] = a[k];
        k--;
      }
      count++;
    }
    for (i = 0; i < n; i++) cout << b[i] << " ";
    cout << "\n";
  }
}
