#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e5 + 5;
const int INF = 1e9;
int a[MAXN], b[MAXN], c[MAXN];
int main() {
  int t;
  scanf("%d", &t);
  while (t--) {
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
      scanf("%d", &a[i]);
    }
    sort(a + 1, a + 1 + n);
    int index1 = 0, index2 = 0;
    for (int i = 1; i <= (n + 1) / 2; i++) {
      b[++index1] = a[i];
    }
    for (int i = (n + 1) / 2 + 1; i <= n; i++) c[++index2] = a[i];
    for (int i = 1; i <= min(index1, index2); i++)
      printf("%d %d ", b[index1 - i + 1], c[i]);
    if (index1 > index2) printf("%d\n", b[1]);
  }
  return 0;
}
