#include"islands.h"
#include<vector>
#include<algorithm>
#include<iostream>
using namespace std;
using ll = long long;
const int mx = 200005;
vector<pair<int, int>> fwd[mx];
vector<pair<int, int>> bck[mx];
int vis[mx];
bool is_cycle[mx];
int N;
int bit;
bool toggle;
bool has_cycle(int cur) {
vis[cur] = 1;
for(auto [nxt, id] : fwd[cur]) {
if(nxt == 0) {
if(toggle) {
if((id >> bit) & 1) continue;
} else {
if(!((id >> bit) & 1)) continue;
}
}
if(vis[nxt] == 0) {
if(has_cycle(nxt)) return true;
} else if(vis[nxt] == 1) {
return true;
}
}
vis[cur] = 2;
return false;
}
std::variant<bool, std::vector<int>> find_journey(int _N, int M, std::vector<int> U, std::vector<int> V) {
N = _N;
return false;
for(int i = 0; i < N; i++) {
fwd[i].clear();
bck[i].clear();
vis[i] = 0;
}
for(int i = 0; i < M; i++) {
fwd[U[i]].push_back({V[i], i});
bck[V[i]].push_back({U[i], i});
}
for(bit = 0; bit < 20; bit++) {
for(int i = 0; i < N; i++) vis[i] = 0;
toggle = false;
if(!has_cycle(0)) continue;
for(int i = 0; i < N; i++) vis[i] = 0;
toggle = true;
if(!has_cycle(0)) continue;
return vector<int>(1, 2);
}
return false;
}
