#include <bits/stdc++.h>
#include "longesttrip.h"
using namespace std;
vector < int > longest_trip(int n, int d) {
bool g = 0;
vector < int > a = {0}, b = {1};
for (int i = 2; i < n; i++) {
if (g) {
if (are_connected({a.back()}, {i})) a.push_back(i), g = 0;
else b.push_back(i);
} else {
if (are_connected({a.back()}, {i})) a.push_back(i);
else if (are_connected({b.back()}, {i})) b.push_back(i), g = 1;
else {
reverse(b.begin(), b.end());
for (auto v : b) a.push_back(v);
b = {i};
}
}
}
if (are_connected(a, b)) {
if (are_connected({a.back()}, {b.back()})) {
reverse(b.begin(), b.end());
for (auto v : b) a.push_back(v);
return a;
} else if (are_connected({a.back()}, {b[0]})) {
for (auto v : b) a.push_back(v);
return a;
} else if (are_connected({a[0]}, {b.back()})) {
for (auto v : a) b.push_back(v);
return b;
} else if (are_connected({a[0]}, {b[0]})) {
reverse(b.begin(), b.end());
for (auto v : a) b.push_back(v);
return b;
} else {
int l = 0, r = (int)a.size() - 1;
while (l < r) {
int mid = (l + r) >> 1;
vector < int > crr;
for (int i = 0; i <= mid; i++) crr.push_back(a[i]);
if (are_connected(crr, b)) r = mid;
else l = mid + 1;
}
int p = l;
l = 0, r = (int)b.size() - 1;
while (l < r) {
int mid = (l + r) >> 1;
vector < int > crr;
for (int i = 0; i <= mid; i++) crr.push_back(b[i]);
if (are_connected({a[p]}, crr)) r = mid;
else l = mid + 1;
}
vector < int > res;
for (int i = (p + 1) % (int)a.size(), s = 0; s < (int)a.size(); s++, i = (i + 1) % (int)a.size()) res.push_back(a[i]);
for (int i = l, s = 0; s < (int)b.size(); s++, i = (i + 1) % (int)b.size()) res.push_back(b[i]);
return res;
}
} else {
return ((int)a.size() > (int)b.size() ? a : b);
}
return {};
}
