#include "bits/stdc++.h"
#include "longesttrip.h"
#define pb push_back
using namespace std;
vector<int> longest_trip(int N, int D){
if(D == 1){
vector<vector<int> > paths;
for(int i = 0; i < N; i++){
paths.pb({i});
}
while(paths.size() > 2){
vector<vector<int> > npaths;
for(int i = 0; i + 2 < paths.size(); i += 3){
int a = paths[i][0], b = paths[i+1][0], c = paths[i+2][0];
bool c1 = are_connected({a}, {b});
bool c2 = are_connected({a}, {c});
bool c3 = are_connected({b}, {c});
if(c1){
vector<int> v = paths[i];
reverse(v.begin(), v.end());
for(auto itr: paths[i+1]) v.pb(itr);
npaths.pb(v);
npaths.pb(paths[i+2]);
}
else if(c2){
vector<int> v = paths[i];
reverse(v.begin(), v.end());
for(auto itr: paths[i+2]) v.pb(itr);
npaths.pb(v);
npaths.pb(paths[i+1]);
}
else if(c3){
vector<int> v = paths[i+1];
reverse(v.begin(), v.end());
for(auto itr: paths[i+2]) v.pb(itr);
npaths.pb(v);
npaths.pb(paths[i]);
}
else{
abort();
}
}
if(paths.size() % 3 >= 1){
npaths.pb(paths[paths.size()-1]);
}
if(paths.size() % 3 >= 2){
npaths.pb(paths[paths.size()-2]);
}
paths = npaths;
}
if(paths[1].size() > paths[0].size()) swap(paths[0], paths[1]);
return paths[0];
}
return {};
}
