This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int maxn = 2e5 + 100;
int n;
vector<pii> g[maxn];
int used[maxn];
bool dfs(int v, int i){
    used[v] = 1;
    for(auto [to, in]: g[v]){
        if(in == i) continue;
        if(used[to]) return 1;
        if(dfs(to, in)) return 1;
    } return 0;
}
std::variant<bool, std::vector<int>> find_journey(
    int N, int M, std::vector<int> U, std::vector<int> V){
    n = N;
    for(int i = 0; i < M; i++){
        int a = U[i] + 1, b = V[i] + 1;
        g[a].push_back({b, i / 2});
    }
    return dfs(1, -1);
}
| # | Verdict  | Execution time | Memory | Grader output | 
|---|
| Fetching results... | 
| # | Verdict  | Execution time | Memory | Grader output | 
|---|
| Fetching results... | 
| # | Verdict  | Execution time | Memory | Grader output | 
|---|
| Fetching results... | 
| # | Verdict  | Execution time | Memory | Grader output | 
|---|
| Fetching results... | 
| # | Verdict  | Execution time | Memory | Grader output | 
|---|
| Fetching results... |