#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    vector<int> A(n);
    for (int i = 0; i < n; ++i) {
      cin >> A[i];
    }
    sort(A.begin(), A.end());
    int j = n - 1, i = 0;
    vector<int> ans;
    while (i < j) {
      ans.push_back(A[j]);
      ans.push_back(A[i]);
      i++;
      j--;
    }
    if (i == j) {
      ans.push_back(A[i]);
    }
    reverse(ans.begin(), ans.end());
    for (i = 0; i < n; ++i) {
      cout << ans[i] << " ";
    }
    cout << endl;
  }
}
