Tifa's CP Library

:heavy_check_mark: src/test_cpverifier/library-checker/cycle_detection.test.cpp

Depends on

Code

#define PROBLEM "https://judge.yosupo.jp/problem/cycle_detection"

#include "../../code/edh/hash_splitmix64.hpp"
#include "../../code/graph/find_cycle.hpp"

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  u32 n, m;
  std::cin >> n >> m;
  tifa_libs::graph::alist g(n);
  tifa_libs::hmap<ptt<u32>, u32> edges;
  for (u32 i = 0, u, v; i < m; ++i) {
    std::cin >> u >> v;
    edges[{u, v}] = i;
    g.add_arc(u, v);
  }
  auto res = tifa_libs::graph::find_cycle<true>(g);
  if (res.empty()) {
    std::cout << "-1\n";
    return 0;
  }
  std::cout << res.size() << '\n';
  for (auto &&i : res) std::cout << edges[i] << '\n';
  return 0;
}
#line 1 "src/test_cpverifier/library-checker/cycle_detection.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/cycle_detection"

#line 1 "src/code/edh/hash_splitmix64.hpp"



#line 1 "src/code/util/traits.hpp"



#line 1 "src/code/util/util.hpp"



#include <bits/stdc++.h>

template <class T>
constexpr T abs(T x) { return x < 0 ? -x : x; }

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using i128 = __int128_t;
using isz = ptrdiff_t;

using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using u128 = __uint128_t;
using usz = size_t;

using f32 = float;
using f64 = double;
using f128 = long double;

template <class T>
using ptt = std::pair<T, T>;
template <class T>
using pt3 = std::tuple<T, T, T>;
template <class T>
using pt4 = std::tuple<T, T, T, T>;

template <class T, usz N>
using arr = std::array<T, N>;
template <class T>
using vec = std::vector<T>;
template <class T>
using vvec = vec<vec<T>>;
template <class T>
using v3ec = vec<vvec<T>>;
template <class U, class T>
using vecp = vec<std::pair<U, T>>;
template <class U, class T>
using vvecp = vvec<std::pair<U, T>>;
template <class T>
using vecpt = vec<ptt<T>>;
template <class T>
using vvecpt = vvec<ptt<T>>;

template <class T, class C = std::less<T>>
using pq = std::priority_queue<T, vec<T>, C>;
template <class T>
using pqg = std::priority_queue<T, vec<T>, std::greater<T>>;

using strn = std::string;
using strnv = std::string_view;

using vecu = vec<u32>;
using vvecu = vvec<u32>;
using v3ecu = v3ec<u32>;
using vecu64 = vec<u64>;
using vecb = vec<bool>;
using vvecb = vvec<bool>;

#ifdef ONLINE_JUDGE
#undef assert
#define assert(x) 42
#endif

using namespace std::literals;

constexpr i8 operator""_i8(unsigned long long x) { return (i8)x; }
constexpr i16 operator""_i16(unsigned long long x) { return (i16)x; }
constexpr i32 operator""_i32(unsigned long long x) { return (i32)x; }
constexpr i64 operator""_i64(unsigned long long x) { return (i64)x; }
constexpr isz operator""_iz(unsigned long long x) { return (isz)x; }

constexpr u8 operator""_u8(unsigned long long x) { return (u8)x; }
constexpr u16 operator""_u16(unsigned long long x) { return (u16)x; }
constexpr u32 operator""_u32(unsigned long long x) { return (u32)x; }
constexpr u64 operator""_u64(unsigned long long x) { return (u64)x; }
constexpr usz operator""_uz(unsigned long long x) { return (usz)x; }

inline const auto fn_0 = [](auto&&...) {};


#line 5 "src/code/util/traits.hpp"

namespace tifa_libs {

template <class T>
concept iterable_c = requires(T v) {
  { v.begin() } -> std::same_as<typename T::iterator>;
  { v.end() } -> std::same_as<typename T::iterator>;
};

template <class T>
concept container_c = iterable_c<T> && !std::derived_from<T, std::basic_string<typename T::value_type>>;

template <class T>
constexpr bool is_char_v = std::is_same_v<T, char> || std::is_same_v<T, signed char> || std::is_same_v<T, unsigned char>;
template <class T>
concept char_c = is_char_v<T>;

template <class T>
constexpr bool is_s128_v = std::is_same_v<T, __int128_t> || std::is_same_v<T, __int128>;
template <class T>
concept s128_c = is_s128_v<T>;

template <class T>
constexpr bool is_u128_v = std::is_same_v<T, __uint128_t> || std::is_same_v<T, unsigned __int128>;
template <class T>
concept u128_c = is_u128_v<T>;

template <class T>
constexpr bool is_i128_v = is_s128_v<T> || is_u128_v<T>;
template <class T>
concept i128_c = is_u128_v<T>;

template <class T>
constexpr bool is_int_v = std::is_integral_v<T> || is_i128_v<T>;
template <class T>
concept int_c = is_int_v<T>;

template <class T>
constexpr bool is_sint_v = is_s128_v<T> || (is_int_v<T> && std::is_signed_v<T>);
template <class T>
concept sint_c = is_sint_v<T>;

template <class T>
constexpr bool is_uint_v = is_u128_v<T> || (is_int_v<T> && std::is_unsigned_v<T>);
template <class T>
concept uint_c = is_uint_v<T>;

template <class T>
concept mint_c = requires(T x) {
  { x.mod() } -> uint_c;
  { x.val() } -> uint_c;
};

template <class T>
constexpr bool is_arithm_v = std::is_arithmetic_v<T> || is_int_v<T>;
template <class T>
concept arithm_c = is_arithm_v<T>;

template <class T>
struct to_sint : std::make_signed<T> {};
template <>
struct to_sint<u128> {
  using type = u128;
};
template <>
struct to_sint<i128> {
  using type = u128;
};
template <class T>
using to_sint_t = typename to_sint<T>::type;

template <class T>
struct to_uint : std::make_unsigned<T> {};
template <>
struct to_uint<u128> {
  using type = u128;
};
template <>
struct to_uint<i128> {
  using type = u128;
};
template <class T>
using to_uint_t = typename to_uint<T>::type;

}  // namespace tifa_libs


#line 5 "src/code/edh/hash_splitmix64.hpp"

namespace tifa_libs {

class hash_splitmix64 {
  static inline u64 seed = 114514;
  static constexpr u64 splitmix64(u64 x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  static constexpr u64 append(u64 x, u64 y) { return x ^ (y >> 1) ^ ((y & 1) << 63); }

 public:
  explicit hash_splitmix64() { set_seed(); }
  explicit constexpr hash_splitmix64(u64 s) { set_seed(s); }

  static void set_seed() { seed = (u64)std::chrono::steady_clock::now().time_since_epoch().count(); }
  static constexpr void set_seed(u64 s) { seed = s; }
  u64 operator()(u64 x) const { return splitmix64(x + seed); }

  template <class T, class U>
  u64 operator()(std::pair<T, U> const &p) const { return append((*this)(p.first), (*this)(p.second)); }
  template <class... Ts>
  u64 operator()(std::tuple<Ts...> const &tp) const {
    u64 ret = 0;
    std::apply([&](Ts const &...targs) { ((ret = append(ret, (*this)(targs))), ...); }, tp);
    return ret;
  }
  template <iterable_c T>
  u64 operator()(T const &tp) const {
    u64 ret = 0;
    for (auto &&i : tp) ret = append(ret, (*this)(i));
    return ret;
  }
};
template <class T>
using hset = std::unordered_set<T, hash_splitmix64>;
template <class K, class V>
using hmap = std::unordered_map<K, V, hash_splitmix64>;

}  // namespace tifa_libs


#line 1 "src/code/graph/find_cycle.hpp"



#line 1 "src/code/graph/alist.hpp"



#line 5 "src/code/graph/alist.hpp"

namespace tifa_libs::graph {

template <bool with_deg = false>
struct alist {
  using weight_type = u32;
  using value_type = vvecu;
  value_type g;
  u32 cnt_arc;
  vecu deg_in;

  //! vertex ID: [0, n)
  explicit constexpr alist(u32 n = 0) : g(n), cnt_arc(0), deg_in(0) {
    if constexpr (with_deg) deg_in.resize(n);
  }

  constexpr void add_arc(u32 u, u32 v) {
    g[u].push_back(v), ++cnt_arc;
    if constexpr (with_deg) ++deg_in[v];
  }
};
template <class G>
concept is_alist = (std::is_base_of_v<alist<true>, G> || std::is_base_of_v<alist<false>, G>);

}  // namespace tifa_libs::graph


#line 5 "src/code/graph/find_cycle.hpp"

namespace tifa_libs::graph {

template <bool directed, bool with_deg>
constexpr vecpt<u32> find_cycle(alist<with_deg> const& fg) {
  auto&& g = fg.g;

  for (u32 i = 0; i < g.size(); ++i)
    for (u32 j : g[i])
      if (i == j) return vecpt<u32>{{i, i}};

  vecu pidx(g.size(), -1_u32), vis(g.size(), 0);

  vecpt<u32> cycle;
  bool fin = false;
  auto dfs = [&](auto&& dfs, u32 now, u32 pval, u32 fa) -> u32 {
    pidx[now] = pval;
    vis[now] = 1;
    for (u32 to : g[now]) {
      if (fin) return -1_u32;
      if constexpr (!directed)
        if (to == fa) continue;
      if (pidx[to] == pidx[now]) {
        cycle.emplace_back(now, to);
        return to;
      }
      if (vis[to]) continue;
      if (u32 nxt = dfs(dfs, to, pval, now); ~nxt) {
        cycle.emplace_back(now, to);
        if (now == nxt) return (fin = true), -1_u32;
        return nxt;
      }
    }
    return pidx[now] = -1_u32;
  };

  for (u32 i = 0; i < g.size(); ++i) {
    if (vis[i]) continue;
    dfs(dfs, i, i, -1_u32);
    if (fin) {
      std::ranges::reverse(cycle);
      return cycle;
    }
  }
  return vecpt<u32>{};
}

}  // namespace tifa_libs::graph


#line 5 "src/test_cpverifier/library-checker/cycle_detection.test.cpp"

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  u32 n, m;
  std::cin >> n >> m;
  tifa_libs::graph::alist g(n);
  tifa_libs::hmap<ptt<u32>, u32> edges;
  for (u32 i = 0, u, v; i < m; ++i) {
    std::cin >> u >> v;
    edges[{u, v}] = i;
    g.add_arc(u, v);
  }
  auto res = tifa_libs::graph::find_cycle<true>(g);
  if (res.empty()) {
    std::cout << "-1\n";
    return 0;
  }
  std::cout << res.size() << '\n';
  for (auto &&i : res) std::cout << edges[i] << '\n';
  return 0;
}

Test cases

Env Name Status Elapsed Memory
g++-12 example_00 :heavy_check_mark: AC 9 ms 4 MB
g++-12 example_01 :heavy_check_mark: AC 8 ms 4 MB
g++-12 example_02 :heavy_check_mark: AC 8 ms 4 MB
g++-12 random_00 :heavy_check_mark: AC 189 ms 48 MB
g++-12 random_01 :heavy_check_mark: AC 243 ms 51 MB
g++-12 random_02 :heavy_check_mark: AC 185 ms 33 MB
g++-12 random_03 :heavy_check_mark: AC 24 ms 19 MB
g++-12 random_04 :heavy_check_mark: AC 51 ms 21 MB
g++-12 random_05 :heavy_check_mark: AC 229 ms 45 MB
g++-12 random_06 :heavy_check_mark: AC 151 ms 37 MB
g++-12 random_07 :heavy_check_mark: AC 14 ms 7 MB
g++-12 random_08 :heavy_check_mark: AC 144 ms 35 MB
g++-12 random_09 :heavy_check_mark: AC 82 ms 22 MB
g++-12 random_dag_00 :heavy_check_mark: AC 266 ms 48 MB
g++-12 random_dag_01 :heavy_check_mark: AC 320 ms 51 MB
g++-12 random_dag_02 :heavy_check_mark: AC 169 ms 32 MB
g++-12 random_dag_03 :heavy_check_mark: AC 24 ms 19 MB
g++-12 random_dag_04 :heavy_check_mark: AC 50 ms 21 MB
g++-12 random_dag_05 :heavy_check_mark: AC 234 ms 44 MB
g++-12 random_dag_06 :heavy_check_mark: AC 128 ms 37 MB
g++-12 random_dag_07 :heavy_check_mark: AC 14 ms 7 MB
g++-12 random_dag_08 :heavy_check_mark: AC 151 ms 34 MB
g++-12 random_dag_09 :heavy_check_mark: AC 82 ms 21 MB
g++-12 random_dag_dense_00 :heavy_check_mark: AC 106 ms 18 MB
g++-12 random_dag_dense_01 :heavy_check_mark: AC 71 ms 7 MB
g++-12 random_dag_dense_02 :heavy_check_mark: AC 58 ms 6 MB
g++-12 random_dag_dense_03 :heavy_check_mark: AC 71 ms 7 MB
g++-12 random_dag_dense_04 :heavy_check_mark: AC 103 ms 14 MB
g++-12 random_dense_00 :heavy_check_mark: AC 112 ms 22 MB
g++-12 random_dense_01 :heavy_check_mark: AC 74 ms 9 MB
g++-12 random_dense_02 :heavy_check_mark: AC 61 ms 7 MB
g++-12 random_dense_03 :heavy_check_mark: AC 75 ms 9 MB
g++-12 random_dense_04 :heavy_check_mark: AC 114 ms 19 MB
Back to top page