#include <bits/stdc++.h>
using namespace std;
int main() {
  int t, n;
  cin >> t;
  while (t--) {
    cin >> n;
    int x;
    vector<long> v;
    vector<long> v1(n);
    for (int i = 0; i < n; i++) {
      cin >> x;
      v.push_back(x);
    }
    sort(v.begin(), v.end());
    int j = v.size() - 1;
    int k = j;
    int l = 0;
    while (l < k) {
      v1[j--] = v[k--];
      v1[j--] = v[l++];
    }
    if (l == k) v1[j] = v[k];
    for (int i = 0; i < n; i++) {
      cout << v1[i] << " ";
    }
    v.clear();
  }
}
