verify/LibraryChecker/graph/connected-components/StronglyConnectedComponents.test.cpp

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Last update: 2025-05-26 06:29:32+09:00
Problem: https://judge.yosupo.jp/problem/scc

Depends on

Code

#include "../../../../template/template.hpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"
#include "../../../../graph/connected-components/StronglyConnectedComponents.hpp"

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n, m;
    in(n, m);
    SCC g(n);

    rep(i, m) {
        int a, b;
        in(a, b);
        g.add_edge(a, b);
    }

    auto res = g.decompose();
    out(res.size());
    for (auto v : res) {
        out(v.size(), v);
    }
}

#line 2 "template/template.hpp"
#pragma region Macros
#include <bits/stdc++.h>
using namespace std;
using lint = long long;
using ull = unsigned long long;
using ld = long double;
using int128 = __int128_t;
#define all(x) (x).begin(), (x).end()
#define uniqv(v) v.erase(unique(all(v)), v.end())
#define OVERLOAD_REP(_1, _2, _3, name, ...) name
#define REP1(i, n) for (auto i = std::decay_t<decltype(n)>{}; (i) != (n); ++(i))
#define REP2(i, l, r) for (auto i = (l); (i) != (r); ++(i))
#define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define logfixed(x) cout << fixed << setprecision(10) << x << endl;

ostream &operator<<(ostream &dest, __int128_t value) {
  ostream::sentry s(dest);
  if (s) {
    __uint128_t tmp = value < 0 ? -value : value;
    char buffer[128];
    char *d = end(buffer);
    do {
      --d;
      *d = "0123456789"[tmp % 10];
      tmp /= 10;
    } while (tmp != 0);
    if (value < 0) {
      --d;
      *d = '-';
    }
    int len = end(buffer) - d;
    if (dest.rdbuf()->sputn(d, len) != len) {
      dest.setstate(ios_base::badbit);
    }
  }
  return dest;
}

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 != (int)v.size() ? " " : "");
  }
  return os;
}

template <typename T>
ostream &operator<<(ostream &os, const set<T> &set_var) {
  for (auto itr = set_var.begin(); itr != set_var.end(); itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}

template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &set_var) {
  for (auto itr = set_var.begin(); itr != set_var.end(); itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}

template <typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &map_var) {
  for (auto itr = map_var.begin(); itr != map_var.end(); itr++) {
    os << itr->first << " -> " << itr->second << "\n";
  }
  return os;
}

template <typename T, typename U>
ostream &operator<<(ostream &os, const unordered_map<T, U> &map_var) {
  for (auto itr = map_var.begin(); itr != map_var.end(); itr++) {
    os << itr->first << " -> " << itr->second << "\n";
  }
  return os;
}

template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &pair_var) {
  os << pair_var.first << " " << pair_var.second;
  return os;
}

void out() { cout << '\n'; }
template <class T, class... Ts>
void out(const T &a, const Ts &...b) {
  cout << a;
  (cout << ... << (cout << ' ', b));
  cout << '\n';
}

void outf() { cout << '\n'; }
template <class T, class... Ts>
void outf(const T &a, const Ts &...b) {
  cout << fixed << setprecision(14) << a;
  (cout << ... << (cout << ' ', b));
  cout << '\n';
}

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

inline void in(void) { return; }
template <typename First, typename... Rest>
void in(First &first, Rest &...rest) {
  cin >> first;
  in(rest...);
  return;
}

template <typename T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

vector<lint> dx8 = {1, 1, 0, -1, -1, -1, 0, 1};
vector<lint> dy8 = {0, 1, 1, 1, 0, -1, -1, -1};
vector<lint> dx4 = {1, 0, -1, 0};
vector<lint> dy4 = {0, 1, 0, -1};

#pragma endregion
#line 2 "verify/LibraryChecker/graph/connected-components/StronglyConnectedComponents.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"
#line 1 "graph/connected-components/StronglyConnectedComponents.hpp"

class SCC {
   private:
    vector<vector<int>> g, r;
    int time;
    int n;
    vector<bool> seen, seen2;
    vector<int> idx;
    int component_id;
    vector<vector<int>> components;

    void dfs(int cur) {
        seen[cur] = true;
        for (auto nex : g[cur]) {
            if (seen[nex] == false) {
                dfs(nex);
            }
        }
        idx[time] = cur;
        time++;
    }

    void dfs2(int cur) {
        seen2[cur] = true;
        components[component_id].emplace_back(cur);
        for (auto nex : r[cur]) {
            if (seen2[nex] == false) {
                dfs2(nex);
            }
        }
    }

   public:
    SCC() {}
    SCC(int siz) {
        n = siz;
        g.resize(n);
        r.resize(n);
        time = 0;
        component_id = 0;
        idx.assign(n, -1);
        seen.assign(n, false);
        seen2.assign(n, false);
    }

    void add_edge(int u, int v) {
        g[u].emplace_back(v);
        r[v].emplace_back(u);
    }

    vector<vector<int>> decompose() {
        for (int i = 0; i < n; i++) {
            if (!seen[i]) {
                dfs(i);
            }
        }

        for (int i = time - 1; i >= 0; i--) {
            if (!seen2[idx[i]]) {
                components.emplace_back(vector<int>());
                dfs2(idx[i]);
                component_id++;
            }
        }

        return components;
    }
};
#line 4 "verify/LibraryChecker/graph/connected-components/StronglyConnectedComponents.test.cpp"

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n, m;
    in(n, m);
    SCC g(n);

    rep(i, m) {
        int a, b;
        in(a, b);
        g.add_edge(a, b);
    }

    auto res = g.decompose();
    out(res.size());
    for (auto v : res) {
        out(v.size(), v);
    }
}