comp-library

This documentation is automatically generated by online-judge-tools/verification-helper

View the Project on GitHub luzhiled1333/comp-library

:heavy_check_mark: test/library-checker/scc.test.cpp

Depends on

Code

// verification-helper: PROBLEM https://judge.yosupo.jp/problem/scc

#include "src/cpp-template/header/fast-ios.hpp"
#include "src/cpp-template/header/int-alias.hpp"
#include "src/cpp-template/header/rep.hpp"
#include "src/cpp-template/header/size-alias.hpp"
#include "src/cpp-template/header/vector-ios.hpp"
#include "src/graph/class/edge/edge.hpp"
#include "src/graph/class/static-graph.hpp"
#include "src/graph/decomposition/strongly-connected-components.hpp"

#include <iostream>
#include <vector>

namespace luz {

  void main_() {
    using edge  = Edge< i32 >;
    using graph = StaticGraph< edge >;

    usize n, m;
    std::cin >> n >> m;
    graph g(n);
    for ([[maybe_unused]] usize _: rep(0, m)) {
      usize u, v;
      std::cin >> u >> v;
      g.add_directed_edge(u, v);
    }

    g.initialize();
    decomposition::StronglyConnectedComponents scc(g);

    auto groups = scc.groups();
    std::cout << groups.size() << std::endl;
    for (auto& group: groups) {
      std::cout << group.size() << " " << group << " " << std::endl;
    }
  }

} // namespace luz

int main() {
  luz::set_fast_ios();

  luz::main_();
}
#line 1 "test/library-checker/scc.test.cpp"
// verification-helper: PROBLEM https://judge.yosupo.jp/problem/scc

#line 2 "src/cpp-template/header/fast-ios.hpp"

#include <iostream>

namespace luz {

  void set_fast_ios() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
  }

} // namespace luz
#line 2 "src/cpp-template/header/int-alias.hpp"

#include <cstdint>

namespace luz {

  using i32  = std::int32_t;
  using i64  = std::int64_t;
  using i128 = __int128_t;

  using u32  = std::uint32_t;
  using u64  = std::uint64_t;
  using u128 = __uint128_t;

} // namespace luz
#line 2 "src/cpp-template/header/rep.hpp"

#line 2 "src/cpp-template/header/size-alias.hpp"

#include <cstddef>

namespace luz {

  using isize = std::ptrdiff_t;
  using usize = std::size_t;

} // namespace luz
#line 4 "src/cpp-template/header/rep.hpp"

#include <algorithm>

namespace luz {

  struct rep {
    struct itr {
      usize i;
      constexpr itr(const usize i) noexcept: i(i) {}
      void operator++() noexcept {
        ++i;
      }
      constexpr usize operator*() const noexcept {
        return i;
      }
      constexpr bool operator!=(const itr x) const noexcept {
        return i != x.i;
      }
    };
    const itr f, l;
    constexpr rep(const usize f, const usize l) noexcept
        : f(std::min(f, l)),
          l(l) {}
    constexpr auto begin() const noexcept {
      return f;
    }
    constexpr auto end() const noexcept {
      return l;
    }
  };

  struct rrep {
    struct itr {
      usize i;
      constexpr itr(const usize i) noexcept: i(i) {}
      void operator++() noexcept {
        --i;
      }
      constexpr usize operator*() const noexcept {
        return i;
      }
      constexpr bool operator!=(const itr x) const noexcept {
        return i != x.i;
      }
    };
    const itr f, l;
    constexpr rrep(const usize f, const usize l) noexcept
        : f(l - 1),
          l(std::min(f, l) - 1) {}
    constexpr auto begin() const noexcept {
      return f;
    }
    constexpr auto end() const noexcept {
      return l;
    }
  };

} // namespace luz
#line 2 "src/cpp-template/header/vector-ios.hpp"

#line 4 "src/cpp-template/header/vector-ios.hpp"

#line 6 "src/cpp-template/header/vector-ios.hpp"
#include <vector>

namespace luz {

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

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

} // namespace luz
#line 2 "src/graph/class/edge/edge.hpp"

#line 4 "src/graph/class/edge/edge.hpp"

#line 6 "src/graph/class/edge/edge.hpp"

namespace luz {

  template < typename T >
  class Edge {
   public:
    using cost_type = T;

    usize from, to;
    T cost;
    usize id;
    Edge() = default;
    Edge(usize from_, usize to_, T cost_, usize id_)
        : from(from_),
          to(to_),
          cost(cost_),
          id(id_) {}
  };

  template < typename T >
  using Edges = std::vector< Edge< T > >;

} // namespace luz
#line 2 "src/graph/class/static-graph.hpp"

#line 5 "src/graph/class/static-graph.hpp"

#line 7 "src/graph/class/static-graph.hpp"
#include <cassert>
#line 9 "src/graph/class/static-graph.hpp"

namespace luz::internal {

  template < typename Iterator >
  class OutgoingEdges {
    Iterator f, l;

   public:
    OutgoingEdges(Iterator f, Iterator l): f(f), l(l) {}

    Iterator begin() const {
      return f;
    }
    Iterator end() const {
      return l;
    }
    usize size() const {
      return l - f;
    }

    auto &operator[](usize k) {
      assert(k < size());
      return begin()[k];
    }
    const auto &operator[](usize k) const {
      assert(k < size());
      return begin()[k];
    }
  };

} // namespace luz::internal

namespace luz {

  template < typename Edge >
  class StaticGraph {

    using Edges          = std::vector< Edge >;
    using iterator       = typename Edges::iterator;
    using const_iterator = typename Edges::const_iterator;

    template < typename Iterator >
    using Es = internal::OutgoingEdges< Iterator >;

   protected:
    bool initialized;
    usize vertex_count;
    usize edge_count;

    Edges edges;
    std::vector< usize > outdegrees;

   public:
    using cost_type = typename Edge::cost_type;

    StaticGraph() = default;
    explicit StaticGraph(usize n)
        : initialized(false),
          vertex_count(n),
          edge_count(0),
          outdegrees(vertex_count) {}

    usize size() const {
      return vertex_count;
    }

    void initialize() {
      assert(not initialized);

      outdegrees.emplace_back(0);
      for (usize i: rrep(0, size())) {
        outdegrees[i] += outdegrees[i + 1];
      }

      std::sort(edges.begin(), edges.end(),
                [](const Edge &e1, const Edge &e2) {
        return e1.from != e2.from ? e1.from > e2.from : e1.to < e2.to;
      });

      initialized = true;
    }

    void add_directed_edge(usize from, usize to, cost_type cost = 1) {
      assert(not initialized);
      assert(from < size());
      assert(to < size());
      edges.emplace_back(from, to, cost, edge_count++);
      outdegrees[from]++;
    }

    void add_undirected_edge(usize u, usize v, cost_type cost = 1) {
      assert(not initialized);
      assert(u < size());
      assert(v < size());
      assert(u != v);
      edges.emplace_back(u, v, cost, edge_count);
      outdegrees[u]++;
      edges.emplace_back(v, u, cost, edge_count++);
      outdegrees[v]++;
    }

    Es< iterator > operator[](const usize &v) {
      assert(initialized);
      return Es< iterator >(edges.begin() + outdegrees[v + 1],
                            edges.begin() + outdegrees[v]);
    }

    const Es< const_iterator > operator[](const usize &v) const {
      assert(initialized);
      return Es< const_iterator >(edges.cbegin() + outdegrees[v + 1],
                                  edges.cbegin() + outdegrees[v]);
    }
  };

} // namespace luz
#line 2 "src/graph/decomposition/strongly-connected-components.hpp"

#line 2 "src/cpp-template/header/change-min.hpp"

namespace luz {

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

} // namespace luz
#line 6 "src/graph/decomposition/strongly-connected-components.hpp"

#line 8 "src/graph/decomposition/strongly-connected-components.hpp"

namespace luz::decomposition {

  template < class G >
  class StronglyConnectedComponents {
    using graph     = G;
    using cost_type = typename graph::cost_type;

    graph g;
    usize g_size;
    std::vector< usize > low, ord, visited, group_id;
    usize ord_cnt, group_cnt;

    void dfs(usize v) {
      low[v] = ord[v] = ord_cnt++;
      visited.emplace_back(v);
      for (auto& e: g[v]) {
        if (ord[e.to] == g_size) {
          dfs(e.to);
          chmin(low[v], low[e.to]);
        } else {
          chmin(low[v], ord[e.to]);
        }
      }
      if (low[v] == ord[v]) {
        while (true) {
          usize u = visited.back();
          visited.pop_back();
          ord[u]      = g_size + 1;
          group_id[u] = group_cnt;
          if (u == v) break;
        }
        group_cnt++;
      }
    }

   public:
    explicit StronglyConnectedComponents(const graph& g_)
        : g(g_),
          g_size(g.size()),
          low(g_size),
          ord(g_size, g_size),
          group_id(g_size),
          ord_cnt(0),
          group_cnt(0) {
      visited.reserve(g_size);
      for (usize v: rep(0, g_size)) {
        if (ord[v] == g_size) {
          dfs(v);
        }
      }
      for (auto& id: group_id) {
        id = group_cnt - id - 1;
      }
    }

    std::vector< std::vector< usize > > groups() const {
      std::vector< usize > counts(group_cnt);
      for (usize i: rep(0, g_size)) {
        counts[group_id[i]]++;
      }
      std::vector< std::vector< usize > > groups(group_cnt);
      for (usize i: rep(0, group_cnt)) {
        groups[i].reserve(counts[i]);
      }
      for (usize i: rep(0, g_size)) {
        groups[group_id[i]].emplace_back(i);
      }
      return groups;
    }

    std::vector< usize > group_ids() const {
      return group_id;
    }
  };

} // namespace luz::decomposition
#line 11 "test/library-checker/scc.test.cpp"

#line 14 "test/library-checker/scc.test.cpp"

namespace luz {

  void main_() {
    using edge  = Edge< i32 >;
    using graph = StaticGraph< edge >;

    usize n, m;
    std::cin >> n >> m;
    graph g(n);
    for ([[maybe_unused]] usize _: rep(0, m)) {
      usize u, v;
      std::cin >> u >> v;
      g.add_directed_edge(u, v);
    }

    g.initialize();
    decomposition::StronglyConnectedComponents scc(g);

    auto groups = scc.groups();
    std::cout << groups.size() << std::endl;
    for (auto& group: groups) {
      std::cout << group.size() << " " << group << " " << std::endl;
    }
  }

} // namespace luz

int main() {
  luz::set_fast_ios();

  luz::main_();
}
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