test/verify/yosupo-cycle-detection.test.cpp

• View this file on GitHub
• Last update: 2024-05-01 23:44:47+09:00
• Problem: https://judge.yosupo.jp/problem/cycle_detection

Depends on

• Graph Template(グラフテンプレート) (graph/graph-template.hpp)
• Cycle Detection(閉路検出) (graph/others/cycle-detection.hpp)
• template/template.hpp

Code

// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/cycle_detection

#include "../../template/template.hpp"

#include "../../graph/others/cycle-detection.hpp"

int main() {
    int N, M;
    cin >> N >> M;
    CycleDetection<> g(N);
    g.read(M, 0, false, true);
    auto ret = g.build();
    if(ret.empty()) {
        cout << -1 << "\n";
    } else {
        cout << ret.size() << "\n";
        for(auto& e : ret) cout << e.idx << "\n";
    }
}

#line 1 "test/verify/yosupo-cycle-detection.test.cpp"
// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/cycle_detection

#line 1 "template/template.hpp"
#include <bits/stdc++.h>

using namespace std;

using int64 = long long;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;

template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << p.first << " " << p.second;
  return os;
}

template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v) is >> in;
  return is;
}

template <typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}

template <typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}

template <typename T = int64>
vector<T> make_v(size_t a) {
  return vector<T>(a);
}

template <typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
  t = v;
}

template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
  for (auto &e : t) fill_v(e, v);
}

template <typename F>
struct FixPoint : F {
  explicit FixPoint(F &&f) : F(forward<F>(f)) {}

  template <typename... Args>
  decltype(auto) operator()(Args &&...args) const {
    return F::operator()(*this, forward<Args>(args)...);
  }
};

template <typename F>
inline decltype(auto) MFP(F &&f) {
  return FixPoint<F>{forward<F>(f)};
}
#line 4 "test/verify/yosupo-cycle-detection.test.cpp"

#line 2 "graph/others/cycle-detection.hpp"

#line 2 "graph/graph-template.hpp"

/**
 * @brief Graph Template(グラフテンプレート)
 */
template <typename T = int>
struct Edge {
  int from, to;
  T cost;
  int idx;

  Edge() = default;

  Edge(int from, int to, T cost = 1, int idx = -1)
      : from(from), to(to), cost(cost), idx(idx) {}

  operator int() const { return to; }
};

template <typename T = int>
struct Graph {
  vector<vector<Edge<T> > > g;
  int es;

  Graph() = default;

  explicit Graph(int n) : g(n), es(0) {}

  size_t size() const { return g.size(); }

  void add_directed_edge(int from, int to, T cost = 1) {
    g[from].emplace_back(from, to, cost, es++);
  }

  void add_edge(int from, int to, T cost = 1) {
    g[from].emplace_back(from, to, cost, es);
    g[to].emplace_back(to, from, cost, es++);
  }

  void read(int M, int padding = -1, bool weighted = false,
            bool directed = false) {
    for (int i = 0; i < M; i++) {
      int a, b;
      cin >> a >> b;
      a += padding;
      b += padding;
      T c = T(1);
      if (weighted) cin >> c;
      if (directed)
        add_directed_edge(a, b, c);
      else
        add_edge(a, b, c);
    }
  }

  inline vector<Edge<T> > &operator[](const int &k) { return g[k]; }

  inline const vector<Edge<T> > &operator[](const int &k) const { return g[k]; }
};

template <typename T = int>
using Edges = vector<Edge<T> >;
#line 4 "graph/others/cycle-detection.hpp"

/**
 * @brief Cycle Detection(閉路検出)
 *
 */
template <typename T = int>
struct CycleDetection : Graph<T> {
  using Graph<T>::Graph;
  using Graph<T>::g;

  vector<int> used;
  Edges<T> pre, cycle;

  bool dfs(int idx) {
    used[idx] = 1;
    for (auto &e : g[idx]) {
      if (used[e] == 0) {
        pre[e] = e;
        if (dfs(e)) return true;
      } else if (used[e] == 1) {
        int cur = idx;
        while (cur != e) {
          cycle.emplace_back(pre[cur]);
          cur = pre[cur].from;
        }
        cycle.emplace_back(e);
        return true;
      }
    }

    used[idx] = 2;
    return false;
  }

  Edges<T> build() {
    used.assign(g.size(), 0);
    pre.resize(g.size());
    for (int i = 0; i < (int)g.size(); i++) {
      if (used[i] == 0 && dfs(i)) {
        reverse(begin(cycle), end(cycle));
        return cycle;
      }
    }
    return {};
  }
};
#line 6 "test/verify/yosupo-cycle-detection.test.cpp"

int main() {
    int N, M;
    cin >> N >> M;
    CycleDetection<> g(N);
    g.read(M, 0, false, true);
    auto ret = g.build();
    if(ret.empty()) {
        cout << -1 << "\n";
    } else {
        cout << ret.size() << "\n";
        for(auto& e : ret) cout << e.idx << "\n";
    }
}

Test cases

Env	Name	Status	Elapsed	Memory
g++	example_00	AC	6 ms	4 MB
g++	example_01	AC	6 ms	4 MB
g++	example_02	AC	6 ms	4 MB
g++	random_00	AC	89 ms	31 MB
g++	random_01	AC	111 ms	34 MB
g++	random_02	AC	71 ms	16 MB
g++	random_03	AC	18 ms	23 MB
g++	random_04	AC	30 ms	18 MB
g++	random_05	AC	94 ms	27 MB
g++	random_06	AC	63 ms	30 MB
g++	random_07	AC	10 ms	8 MB
g++	random_08	AC	62 ms	23 MB
g++	random_09	AC	40 ms	13 MB
g++	random_dag_00	AC	115 ms	31 MB
g++	random_dag_01	AC	106 ms	34 MB
g++	random_dag_02	AC	68 ms	16 MB
g++	random_dag_03	AC	18 ms	23 MB
g++	random_dag_04	AC	31 ms	18 MB
g++	random_dag_05	AC	113 ms	27 MB
g++	random_dag_06	AC	61 ms	29 MB
g++	random_dag_07	AC	10 ms	8 MB
g++	random_dag_08	AC	71 ms	23 MB
g++	random_dag_09	AC	44 ms	13 MB
g++	random_dag_dense_00	AC	46 ms	13 MB
g++	random_dag_dense_01	AC	46 ms	12 MB
g++	random_dag_dense_02	AC	45 ms	12 MB
g++	random_dag_dense_03	AC	46 ms	12 MB
g++	random_dag_dense_04	AC	52 ms	14 MB
g++	random_dense_00	AC	46 ms	15 MB
g++	random_dense_01	AC	46 ms	14 MB
g++	random_dense_02	AC	44 ms	14 MB
g++	random_dense_03	AC	46 ms	14 MB
g++	random_dense_04	AC	50 ms	13 MB
clang++	example_00	AC	6 ms	4 MB
clang++	example_01	AC	6 ms	4 MB
clang++	example_02	AC	6 ms	4 MB
clang++	random_00	AC	83 ms	31 MB
clang++	random_01	AC	136 ms	34 MB
clang++	random_02	AC	69 ms	16 MB
clang++	random_03	AC	17 ms	23 MB
clang++	random_04	AC	30 ms	18 MB
clang++	random_05	AC	85 ms	27 MB
clang++	random_06	AC	70 ms	30 MB
clang++	random_07	AC	10 ms	8 MB
clang++	random_08	AC	64 ms	23 MB
clang++	random_09	AC	38 ms	13 MB
clang++	random_dag_00	AC	97 ms	31 MB
clang++	random_dag_01	AC	133 ms	34 MB
clang++	random_dag_02	AC	69 ms	16 MB
clang++	random_dag_03	AC	18 ms	23 MB
clang++	random_dag_04	AC	29 ms	18 MB
clang++	random_dag_05	AC	89 ms	27 MB
clang++	random_dag_06	AC	61 ms	29 MB
clang++	random_dag_07	AC	10 ms	8 MB
clang++	random_dag_08	AC	73 ms	23 MB
clang++	random_dag_09	AC	43 ms	13 MB
clang++	random_dag_dense_00	AC	46 ms	13 MB
clang++	random_dag_dense_01	AC	46 ms	12 MB
clang++	random_dag_dense_02	AC	44 ms	12 MB
clang++	random_dag_dense_03	AC	46 ms	12 MB
clang++	random_dag_dense_04	AC	52 ms	14 MB
clang++	random_dense_00	AC	45 ms	15 MB
clang++	random_dense_01	AC	46 ms	14 MB
clang++	random_dense_02	AC	44 ms	14 MB
clang++	random_dense_03	AC	46 ms	14 MB
clang++	random_dense_04	AC	51 ms	13 MB

Back to top page