#include <bits/stdc++.h>
using namespace std;
#define ll int
#define vll vector<ll>
#define pb push_back
bool are_connected(std::vector<int> A, std::vector<int> B);
std::vector<int> longest_trip(int n, int D)
{
if(D==3)
{
vector<int> ans;
for(int i=0;i<n;i++)
ans.push_back(i);
return ans;
}
else if(D==2)
{
vector<int> ans;
for(int i=n-1;i>0;i--)
ans.pb(i);
ll s=0;
vll order={0};
while(ans.size()>1)
{
ll f1=ans.back();
ans.pop_back();
ll f2=ans.back();
ans.pop_back();
bool r1=are_connected({s},{f1});
bool r2=are_connected({s},{f2});
bool r3=are_connected({f1},{f2});
if(r1 and r3)
{
order.pb(f1);
order.pb(f2);
}
else if(r2 and r3)
{
order.pb(f2);
order.pb(f1);
}
s=order.back();
}
if(ans.size()>0)
{
ll l=ans.back();
bool r1=are_connected({s},{l});
if(r1)
order.pb(l);
}
return order;
}
return {};
}
