#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 10;
long long aa[maxn], ans[maxn];
void solve() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%lld", &aa[i]);
  }
  sort(aa + 1, aa + 1 + n);
  int l = 1, r = n, cnt = n;
  for (int i = 1; i <= n / 2; i++) {
    ans[cnt--] = aa[l];
    ans[cnt--] = aa[r];
    l++, r--;
  }
  if (n % 2) {
    ans[1] = aa[n / 2 + 1];
  }
  for (int i = 1; i <= n; i++) {
    printf("%d ", ans[i]);
  }
  printf("\n");
}
int main() {
  int T;
  scanf("%d", &T);
  while (T--) {
    solve();
  }
  return 0;
}
