#include <bits/stdc++.h>
using namespace std;
#include "longesttrip.h"
vector<int> subrange(vector<int> &V, int l, int r){
vector<int> res(V.begin() + l, V.begin() + r + 1);
return res;
}
vector<int> longest_trip(int N, int D){
// Assuming D = 1
vector<int> v1 = {0}, v2 = {1};
for (int i = 2; i < N; i++){
if (are_connected({v1.back()}, {i})) v1.push_back(i);
else if (are_connected({v2.back()}, {i})) v2.push_back(i);
else{
reverse(v2.begin(), v2.end());
v1.insert(v1.end(), v2.begin(), v2.end());
v2.clear(); v2.push_back(i);
}
}
if (are_connected({v1.front()}, {v2.front()})){
reverse(v1.begin(), v1.end());
v2.insert(v2.begin(), v1.begin(), v1.end());
return v2;
}
if (are_connected({v1.back()}, {v2.front()})){
v2.insert(v2.begin(), v1.begin(), v1.end());
return v2;
}
if (are_connected({v1.front()}, {v2.back()})){
v2.insert(v2.end(), v1.begin(), v1.end());
return v2;
}
if (are_connected({v1.back()}, {v2.back()})){
reverse(v1.begin(), v1.end());
v2.insert(v2.end(), v1.begin(), v1.end());
return v2;
}
int l1 = 0, r1 = v1.size() - 1;
int l2 = 0, r2 = v2.size() - 1;
while (l1 < r1){
int mid = (l1 + r1) >> 1;
bool edge = are_connected(subrange(v1, l1, mid), subrange(v2, l2, r2));
if (edge) r1 = mid;
else l1 = mid + 1;
}
while (l2 < r2){
int mid = (l2 + r2) >> 1;
bool edge = are_connected(subrange(v1, l1, r1), subrange(v2, l2, mid));
if (edge) r2 = mid;
else l2 = mid + 1;
}
vector<int> res1, res2;
for (int i = l1; i < (int)v1.size(); i++) res1.push_back(v1[i]);
for (int i = 0; i < l1; i++) res1.push_back(v1[i]);
for (int i = l2; i < (int)v2.size(); i++) res2.push_back(v2[i]);
for (int i = 0; i < l2; i++) res2.push_back(v2[i]);
reverse(res1.begin(), res1.end());
res2.insert(res2.begin(), res1.begin(), res1.end());
return res2;
}
