#include <bits/stdc++.h>
using namespace std;
using ULL = unsigned long long;
using UL = unsigned;
using LL = long long;
template <class Ty>
using passive_queue = priority_queue<Ty, vector<Ty>, greater<Ty>>;
struct Problem {
  void Loop() {
    UL N;
    cin >> N;
    vector<int> A(N);
    for (UL i = 0; i < (N); i++) cin >> A[i];
    sort(A.begin(), A.end());
    int p = 0, q = N - 1;
    vector<int> ans;
    while (p <= q) {
      ans.push_back(A[p]);
      if (p < q) ans.push_back(A[q]);
      p++;
      q--;
    }
    reverse(ans.begin(), ans.end());
    for (UL i = 0; i < (N); i++) {
      if (i) cout << " ";
      cout << ans[i];
    }
    cout << endl;
  }
  void Solve() {
    UL Q;
    cin >> Q;
    for (UL i = 0; i < (Q); i++) {
      Loop();
    }
  }
  Problem();
};
int main() {
  unique_ptr<Problem> p(new Problem());
  p->Solve();
  return 0;
}
Problem::Problem() { cout << fixed << setprecision(10); }
