lmori's Library

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:heavy_check_mark: verify/LibraryChecker/graph/connected-components/TwoEdgeConnectedComponents.test.cpp

Depends on

Code

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

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

    rep(i, m) {
        int u, v;
        in(u, v);
        g.add_edge(u, v);
    }
    g.build();

    out(g.components.size());
    for (auto &v : g.components) {
        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/TwoEdgeConnectedComponents.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/two_edge_connected_components"
#line 1 "graph/others/LowLink.hpp"
class LowLink {
   public:
    int n, time;
    vector<vector<pair<int, int>>> g;
    vector<bool> seen;
    vector<int> order, low;
    vector<int> articulation;
    vector<int> bridge;

    LowLink(int _n) : n(_n), time(0) {
        g.resize(n);
        seen.assign(n, false);
        order.assign(n, -1);
        low.assign(n, 0);
    }

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

    void dfs(int cur, int prev, int prev_eid) {
        seen[cur] = true;
        order[cur] = low[cur] = time++;
        int child = 0;
        bool is_articulation = false;
        for (auto &[nex, eid] : g[cur]) {
            if (!seen[nex]) {
                child++;
                dfs(nex, cur, eid);
                low[cur] = min(low[cur], low[nex]);
                if (prev != -1 and order[cur] <= low[nex]) is_articulation = true;
                if (order[cur] < low[nex]) bridge.push_back(eid);
            } else if (eid != prev_eid) {
                low[cur] = min(low[cur], order[nex]);
            }
        }
        if (prev == -1 and child > 1) is_articulation = true;
        if (is_articulation) articulation.push_back(cur);
    }

    void build() {
        for (int i = 0; i < n; i++) {
            if (!seen[i]) dfs(i, -1, -1);
        }
    }
};
#line 2 "graph/connected-components/TwoEdgeConnectedComponents.hpp"

class TwoEdgeConnectedComponents {
   private:
    int n;
    int m;
    int eid;
    vector<pair<int, int>> edges;
    LowLink l;

    void dfs(int v, int prev, int prev_eid, const vector<bool> &is_bridge, int cid) {
        cmp[v] = cid;
        for (auto &[nex, eid] : l.g[v]) {
            if (cmp[nex] == -1 and !is_bridge[eid]) {
                dfs(nex, v, eid, is_bridge, cid);
            }
        }
    }

   public:
    vector<int> cmp;
    vector<vector<int>> components;

    TwoEdgeConnectedComponents(int _n) : n(_n), l(_n), eid(0) {
        cmp.assign(n, -1);
    }

    void add_edge(int u, int v) {
        l.add_edge(u, v, eid);
        edges.emplace_back(u, v);
        eid++;
    }

    void build() {
        l.build();
        vector<bool> is_bridge(eid, false);
        for (int id : l.bridge) is_bridge[id] = true;

        int cid = 0;
        for (int i = 0; i < n; i++) {
            if (cmp[i] == -1) {
                dfs(i, -1, -1, is_bridge, cid++);
            }
        }
        components.resize(cid);
        for (int i = 0; i < n; i++) {
            components[cmp[i]].push_back(i);
        }
    }
};
#line 4 "verify/LibraryChecker/graph/connected-components/TwoEdgeConnectedComponents.test.cpp"

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

    rep(i, m) {
        int u, v;
        in(u, v);
        g.add_edge(u, v);
    }
    g.build();

    out(g.components.size());
    for (auto &v : g.components) {
        out(v.size(), v);
    }
}
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