#include <bits/stdc++.h>
using namespace std;
bool comp(pair<long long, long long> a, pair<long long, long long> b) {
  return a.first == b.first && a.second == b.second;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t, n, i, j;
  vector<long long> v, ans;
  cin >> t;
  while (t--) {
    v.clear();
    ans.clear();
    cin >> n;
    for (i = 0; i < n; i++) {
      cin >> j;
      v.push_back(j);
    }
    sort(v.begin(), v.end());
    i = 0;
    j = n - 1;
    while (i <= j) {
      if (i < j) {
        ans.push_back(v[i]);
        ans.push_back(v[j]);
      } else
        ans.push_back(v[i]);
      j--;
      i++;
    }
    for (i = n - 1; i >= 0; i--) {
      cout << ans[i] << " ";
    }
    cout << endl;
  }
  return 0;
}
