Codeforces Round #633 (Div. 2) B. Sorted Adjacent Differences

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