#include <bits/stdc++.h>
using namespace std;
vector<int> inpVec(int n) {
  vector<int> v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  return v;
}
void printVec(vector<int> v) {
  for (int i = 0; i < v.size(); i++) cout << v[i] << " ";
  cout << endl;
}
int main() {
  std::ios_base::sync_with_stdio(false);
  int t = 1;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    vector<int> v = inpVec(n);
    sort(v.begin(), v.end());
    int start = 0;
    int end = n - 1;
    vector<int> ans;
    while (start < end) {
      ans.push_back(v[end--]);
      ans.push_back(v[start++]);
    }
    if (start == end) ans.push_back(v[start]);
    reverse(ans.begin(), ans.end());
    printVec(ans);
  }
  return 0;
}
