#include<iostream>
#include<bits/stdc++.h>
using namespace std;
// #Problem #Arrays #GFG
// https://www.geeksforgeeks.org/program-print-array-pendulum-arrangement/
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());
vector<int> pendulum(n);
int l,r;
if(n%2==0){
l=(n-1)/2; // initializing l and r at midpoint
r=(n-1)/2;
}else{
l=n/2;
r=n/2;
}
pendulum[l]=a[0]; // filling in the mid point
int counter=0; // to count odd or even step
int i=1; // iterator to fill in elements from sorted array
while(i<n){
if(counter%2==0){
r++; // move right and fill
pendulum[r]=a[i];
}else{
l--; // move left and fill
pendulum[l]=a[i];
}
counter++;
i++;
}
for(int i=0;i<n;i++){
cout<<pendulum[i]<<" ";
}
cout<<endl;
}
return 0;
}