test/yosupo-judge/scc/main.test.cpp

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• Last update: 2021-04-23 23:44:44+09:00
• Problem: https://judge.yosupo.jp/problem/scc
• Link: View error logs on GitHub Actions

Depends on

• Strongly connected components (Mylib/Graph/GraphUtils/strongly_connected_components.cpp)
• Basic graph (Mylib/Graph/Template/graph.cpp)
• join function (Mylib/IO/join.cpp)

Code

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

#include <iostream>
#include <vector>
#include "Mylib/Graph/GraphUtils/strongly_connected_components.cpp"
#include "Mylib/Graph/Template/graph.cpp"
#include "Mylib/IO/join.cpp"

namespace hl = haar_lib;

int main() {
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);

  int N, M;
  std::cin >> N >> M;

  hl::graph<int> g(N);
  g.read<0, true, false>(M);

  auto [scc, K] = hl::strongly_connected_components(g);
  std::vector<std::vector<int>> ans(K);
  for (int i = 0; i < N; ++i) ans[scc[i]].push_back(i);

  std::cout << K << "\n";

  for (auto &t : ans) {
    std::cout << t.size() << " " << hl::join(t.begin(), t.end()) << "\n";
  }

  return 0;
}

#line 1 "test/yosupo-judge/scc/main.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"

#include <iostream>
#include <vector>
#line 2 "Mylib/Graph/GraphUtils/strongly_connected_components.cpp"
#include <algorithm>
#line 4 "Mylib/Graph/Template/graph.cpp"

namespace haar_lib {
  template <typename T>
  struct edge {
    int from, to;
    T cost;
    int index = -1;
    edge() {}
    edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
    edge(int from, int to, T cost, int index) : from(from), to(to), cost(cost), index(index) {}
  };

  template <typename T>
  struct graph {
    using weight_type = T;
    using edge_type   = edge<T>;

    std::vector<std::vector<edge<T>>> data;

    auto& operator[](size_t i) { return data[i]; }
    const auto& operator[](size_t i) const { return data[i]; }

    auto begin() const { return data.begin(); }
    auto end() const { return data.end(); }

    graph() {}
    graph(int N) : data(N) {}

    bool empty() const { return data.empty(); }
    int size() const { return data.size(); }

    void add_edge(int i, int j, T w, int index = -1) {
      data[i].emplace_back(i, j, w, index);
    }

    void add_undirected(int i, int j, T w, int index = -1) {
      add_edge(i, j, w, index);
      add_edge(j, i, w, index);
    }

    template <size_t I, bool DIRECTED = true, bool WEIGHTED = true>
    void read(int M) {
      for (int i = 0; i < M; ++i) {
        int u, v;
        std::cin >> u >> v;
        u -= I;
        v -= I;
        T w = 1;
        if (WEIGHTED) std::cin >> w;
        if (DIRECTED)
          add_edge(u, v, w, i);
        else
          add_undirected(u, v, w, i);
      }
    }
  };

  template <typename T>
  using tree = graph<T>;
}  // namespace haar_lib
#line 5 "Mylib/Graph/GraphUtils/strongly_connected_components.cpp"

namespace haar_lib {
  template <typename T>
  auto strongly_connected_components(const graph<T> &g) {
    const int n = g.size();

    std::vector<int> ret(n), low(n, -1), ord(n, -1), S;
    std::vector<bool> check(n);
    S.reserve(n);
    int t = 0;
    int k = 0;

    auto dfs =
        [&](auto &dfs, int cur) -> void {
      low[cur] = ord[cur] = t++;
      S.push_back(cur);
      check[cur] = true;

      for (auto &e : g[cur]) {
        if (ord[e.to] == -1) {
          dfs(dfs, e.to);
          low[cur] = std::min(low[cur], low[e.to]);
        } else if (check[e.to]) {
          low[cur] = std::min(low[cur], low[e.to]);
        }
      }

      if (low[cur] == ord[cur]) {
        while (true) {
          int u = S.back();
          S.pop_back();
          check[u] = false;
          ret[u]   = k;
          if (cur == u) break;
        }
        ++k;
      }
    };

    for (int i = 0; i < n; ++i) {
      if (ord[i] == -1) {
        t = 0;
        dfs(dfs, i);
      }
    }

    for (auto &x : ret) x = k - 1 - x;

    return std::make_pair(ret, k);
  }
}  // namespace haar_lib
#line 3 "Mylib/IO/join.cpp"
#include <sstream>
#include <string>

namespace haar_lib {
  template <typename Iter>
  std::string join(Iter first, Iter last, std::string delim = " ") {
    std::stringstream s;

    for (auto it = first; it != last; ++it) {
      if (it != first) s << delim;
      s << *it;
    }

    return s.str();
  }
}  // namespace haar_lib
#line 8 "test/yosupo-judge/scc/main.test.cpp"

namespace hl = haar_lib;

int main() {
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);

  int N, M;
  std::cin >> N >> M;

  hl::graph<int> g(N);
  g.read<0, true, false>(M);

  auto [scc, K] = hl::strongly_connected_components(g);
  std::vector<std::vector<int>> ans(K);
  for (int i = 0; i < N; ++i) ans[scc[i]].push_back(i);

  std::cout << K << "\n";

  for (auto &t : ans) {
    std::cout << t.size() << " " << hl::join(t.begin(), t.end()) << "\n";
  }

  return 0;
}

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