#include <bits/stdc++.h>
using namespace std;
void mahol() {
  long long int n;
  cin >> n;
  vector<long long int> a(n);
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  };
  sort(a.begin(), a.end());
  vector<long long int> ans;
  for (long long int i = 0; i < n / 2; i++) {
    ans.push_back(a[i]);
    ans.push_back(a[n - i - 1]);
  }
  if (n % 2 != 0) {
    ans.push_back(a[n / 2]);
  }
  reverse(ans.begin(), ans.end());
  for (long long int i = 0; i < (long long int)((ans).size()); i++) {
    cout << ans[i] << " ";
  };
  cout << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int t;
  cin >> t;
  while (t--) {
    mahol();
  }
  return 0;
}
