#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;
    cin >> n;
    long long int arr[n];
    for (long long int i = 0; i < n; i++) cin >> arr[i];
    sort(arr, arr + n);
    long long int i = 0, j = n - 1;
    vector<long long int> ans;
    while (i <= j) {
      if (i == j)
        ans.push_back(arr[i]);
      else {
        ans.push_back(arr[j]);
        ans.push_back(arr[i]);
      }
      i++;
      j--;
    }
    reverse(ans.begin(), ans.end());
    for (auto i : ans) cout << i << " ";
    cout << endl;
  }
  return 0;
}
