#include <bits/stdc++.h>
using namespace std;
long long a[100005];
void solve() {
  long long n;
  cin >> n;
  for (long long i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  vector<long long> ans;
  long long st = 0, end = n - 1;
  while (end > st) {
    ans.push_back(a[end]);
    ans.push_back(a[st]);
    st++;
    end--;
  }
  if (st == end) {
    ans.push_back(a[st]);
  }
  reverse((ans).begin(), (ans).end());
  for (auto i : ans) {
    cout << i << " ";
  }
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  cin >> t;
  while (t--) {
    solve();
    cout << '\n';
  }
  return 0;
}
