BST

#include <bits/stdc++.h>

#define ll long long
#define el endl
#define umi unordered_map<int, int>
#define umll unordered_map<ll, ll>
#define all(vect) vect.begin(), vect.end()
#define reset(A) memset(A, 0, sizeof(A))

const int mod = 1e9 + 7;

using namespace std;

struct node
{
    int val;
    node *l, *r;
};

node *create(int x)
{
    node *p = new node;
    p->val = x;
    p->l = NULL;
    p->r = NULL;
    return p;
}

node *addL(node *p, int x)
{
    node *temp = p;
    node *te1 = create(x);
    temp->l = te1;
    return temp;
}

node *addR(node *p, int x)
{
    node *temp = p;
    node *te1 = create(x);
    temp->r = te1;
    return temp;
}

void travel(node *root, int x)
{
    node *p = root;
    if(p->val < x && p->l == NULL)
        p = addL(p, x);
    else if(p->val > x && p->r == NULL)
        p = addR(p, x);
    else if(p->val < x && p->l != NULL)
        travel(p->l, x);
    else if(p->val > x && p->r != NULL)
        travel(p->r, x);
}

void post(node *root)
{
    node *p = root;
    if(p->r != NULL)
        post(p->r);
    if(p->l != NULL)
        post(p->l);

    cout << p->val << " ";
}

void solve()
{
    int n;
    cin >> n;
    int a;
    cin >> a;
    n--;
    node *root = create(a);
    node *te = root;
    while(n--)
    {
        cin >> a;
        travel(te, a);
    }
    node *tem0 = root;
    post(tem0);
    cout << el;
}

int main()
{
    int t = 1;
    cin >> t;
    while(t--)
    {
        solve();
    }
    return 0;
}