Cycle Detection (Undirected) (verify/graph/cycle_undirected.test.cpp)

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• Last update: 2026-04-22 09:17:08-07:00
• Problem: https://judge.yosupo.jp/problem/cycle_detection_undirected

Depends on

• cp-algo/graph/base.hpp
• cp-algo/graph/concepts.hpp
• cp-algo/graph/cycle.hpp
• cp-algo/graph/dfs.hpp
• cp-algo/graph/edge_types.hpp
• cp-algo/structures/stack_union.hpp
• cp-algo/util/big_alloc.hpp

Code

// @brief Cycle Detection (Undirected)
#define PROBLEM "https://judge.yosupo.jp/problem/cycle_detection_undirected"
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include "cp-algo/graph/cycle.hpp"
#include <bits/stdc++.h>

using namespace std;
using namespace cp_algo::graph;

void solve() {
    int n, m;
    cin >> n >> m;
    graph g(n);
    g.read_edges(m);
    auto [v, cycle] = find_cycle(g);
    if(empty(cycle)) {
        cout << -1 << "\n";
    } else {
        cout << size(cycle) << "\n";
        cout << v;
        for(auto it: cycle | views::take(size(cycle) - 1)) {
            v = g.edge(it).traverse(v);
            cout << ' ' << v;
        }
        cout << "\n";
        for(auto it: cycle) {cout << it << ' ';}
        cout << "\n";
    }
}

signed main() {
    //freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    while(t--) {
        solve();
    }
}

Traceback (most recent call last):
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/resolver.py", line 290, in resolve
    bundled_code = language.bundle(path, basedir=basedir)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/languages/cplusplus.py", line 243, in bundle
    bundler.update(path)
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/languages/cplusplus_bundle.py", line 322, in update
    assert len(lines) == len(uncommented_lines)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

Test cases

Env	Name	Status	Elapsed	Memory
g++	example_00	AC	3 ms	4 MB
g++	example_01	AC	2 ms	4 MB
g++	example_02	AC	2 ms	4 MB
g++	example_03	AC	2 ms	4 MB
g++	example_04	AC	2 ms	4 MB
g++	long_cycle_00	AC	118 ms	26 MB
g++	long_cycle_01	AC	114 ms	29 MB
g++	long_cycle_02	AC	16 ms	6 MB
g++	random_00	AC	53 ms	23 MB
g++	random_01	AC	52 ms	23 MB
g++	random_02	AC	43 ms	20 MB
g++	random_03	AC	11 ms	7 MB
g++	random_04	AC	25 ms	9 MB
g++	random_05	AC	51 ms	22 MB
g++	random_06	AC	35 ms	15 MB
g++	random_07	AC	6 ms	4 MB
g++	random_08	AC	42 ms	19 MB
g++	random_09	AC	26 ms	12 MB
g++	random_dense_00	AC	40 ms	22 MB
g++	random_dense_01	AC	43 ms	22 MB
g++	random_dense_02	AC	41 ms	23 MB
g++	tree_00	AC	73 ms	22 MB
g++	tree_01	AC	86 ms	25 MB
g++	tree_02	AC	11 ms	5 MB
g++	unicyclic_00	AC	65 ms	22 MB
g++	unicyclic_01	AC	62 ms	25 MB
g++	unicyclic_02	AC	10 ms	5 MB

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