#include "islands.h"
#include <variant>
#include <algorithm>
#include <bitset>
#include <cstdint>
#include <cstring>
#include <iostream>
#include <limits.h>
#include <math.h>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
//#define int long long
#define loop(X, N) for(int X = 0; X < (N); X++)
#define all(V) V.begin(), V.end()
#define rall(V) V.rbegin(), V.rend()
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<vector<ii>> vvii;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef uint64_t u64;
typedef int64_t i64;
int n, m;
vvii adj;
vb vis;
vi succesPath;
bool success = false;
vi path;
int dfs2(int node, int parent) {
if (vis[node]) {
return 1;
}
vis[node] = true;
int count = 0;
vi validPaths;
for (auto [child, idx] : adj[node]) {
if (child == parent) continue;
path.push_back(idx);
int res = dfs2(child, node);
path.pop_back();
if (res >= 1 && count < 2) {
count++;
validPaths.push_back(idx);
}
}
if (count >= 2 && !success) {
success = true;
succesPath = path;
succesPath.push_back(validPaths[0]);
succesPath.push_back(validPaths[0] ^ 1);
succesPath.push_back(validPaths[1]);
succesPath.push_back(validPaths[1] ^ 1);
succesPath.push_back(validPaths[0] ^ 1);
succesPath.push_back(validPaths[0]);
succesPath.push_back(validPaths[1] ^ 1);
succesPath.push_back(validPaths[1]);
for (int i = path.size() - 1; i >= 0; i--) {
succesPath.push_back(path[i]);
}
}
return 1;
}
std::variant<bool, std::vector<int>> find_journey(int N, int M, vi U, vi V) {
n = N;
m = M;
adj = vvii(n);
loop(i, m) {
adj[U[i]].push_back({V[i], i});
}
vis = vb(n);
success = false;
path = vi();
dfs2(0, -1);
if (success) {
for (int x : succesPath) {
cerr << x << ' ';
}
cerr << endl;
return succesPath;
}
return false;
// return false;
// return success;
}
