#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long tc = 1;
  cin >> tc;
  while (tc--) {
    long long n;
    cin >> n;
    long long arr[n];
    for (long long i = 0; i < n; i++) cin >> arr[i];
    sort(arr, arr + n);
    long long ans[n];
    long long i = 0, j = n - 1, ind = 0;
    while (i <= j) {
      ans[ind] = arr[i];
      ind++;
      if (ind < n) ans[ind] = arr[j];
      ind++, i++, j--;
    }
    for (long long i = n - 1; i >= 0; i--) cout << ans[i] << " ";
    cout << endl;
  }
}
