#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
#define arr array
#define vec vector
#define var variant
#define pii pair<int, int>
#define fir first
#define sec second
const int N = 1e5 + 5;
int n, m;
arr<vec<int>, N> adj;
map<pii, int> id;
vec<int> stk, cyc;
arr<bool, N> vs;
bool dfs(int u = 1) {
vs[u] = true;
stk.push_back(u);
for (int v : adj[u]) {
if (!vs[v]) {
if (dfs(v)) return true;
continue;
}
while (true) {
int w = stk.back(); stk.pop_back();
cyc.push_back(w);
if (w == v) break;
}
reverse(cyc.begin(), cyc.end());
return true;
}
stk.pop_back();
return false;
}
var<bool, vec<int>> find_journey(int _n, int _m, vec<int> _u, vec<int> _v) {
n = _n, m = _m;
for (int i = 0; i < m; i++) {
int u = _u[i] + 1, v = _v[i] + 1;
adj[u].push_back(v);
id[{u, v}] = i;
}
if (!dfs()) return false;
return true;
}
