cpl

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:heavy_check_mark: graph/test/scc.test.cpp

Depends on

Code

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

#define FAST_IO

#include "../../template/template.hpp"
#include "../../graph/graph.hpp"
#include "../../graph/strongly_connected_components.hpp"

int main() {
    i32 n, m;
    cin >> n >> m;
    Graph<i32> g(n);
    REP(e, m) {
        i32 u, v;
        cin >> u >> v;
        g.add_directed_edge(u, v);
    }
    StronglyConnectedComponents<Graph<i32>> scc(g);
    Vec<Vec<i32>> groups = scc.groups();
    cout << groups.size() << '\n';
    for (const Vec<i32> &group : groups) {
        cout << group.size();
        for (i32 v : group) {
            cout << ' ' << v;
        }
        cout << '\n';
    }
}
#line 1 "graph/test/scc.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"

#define FAST_IO

#line 1 "template/template.hpp"
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32) (n); ++i)
#define REP3(i, m, n) for (i32 i = (i32) (m); i < (i32) (n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER(i, n) for (i32 i = (i32) (n) - 1; i >= 0; --i)
#define ALL(x) begin(x), end(x)

using namespace std;

using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = __uint128_t;
using i32 = signed int;
using i64 = signed long long;
using i128 = __int128_t;
using f64 = double;
using f80 = long double;

template <typename T>
using Vec = vector<T>;

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

istream &operator>>(istream &is, i128 &x) {
    i64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, i128 x) {
    os << (i64) x;
    return os;
}
istream &operator>>(istream &is, u128 &x) {
    u64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, u128 x) {
    os << (u64) x;
    return os;
}

[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;
struct SetUpIO {
    SetUpIO() {
#ifdef FAST_IO
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
#endif
        cout << fixed << setprecision(15);
    }
} set_up_io;
#line 2 "graph/graph.hpp"

#line 7 "graph/graph.hpp"

template <typename Edge>
class Graph {
    std::vector<std::vector<Edge>> edges;

public:
    Graph() : edges() {}
    Graph(int v) : edges(v) {
        assert(v >= 0);
    }
    
    std::vector<int> add_vertices(int n) {
        int v = (int) edges.size();
        std::vector<int> idx(n);
        std::iota(idx.begin(), idx.end(), v);
        edges.resize(edges.size() + n);
        return idx;
    }

    template <typename... T>
    void add_directed_edge(int from, int to, T &&...val) {
        assert(from >= 0 && from < (int) edges.size());
        assert(to >= 0 && to < (int) edges.size());
        edges[from].emplace_back(Edge(to, std::forward<T>(val)...));
    }

    template <typename... T>
    void add_undirected_edge(int u, int v, const T &...val) {
        assert(u >= 0 && u < (int) edges.size());
        assert(v >= 0 && v < (int) edges.size());
        edges[u].emplace_back(Edge(v, val...));
        edges[v].emplace_back(Edge(u, val...));
    }

    int size() const {
        return (int) edges.size();
    }

    const std::vector<Edge> &operator[](int v) const {
        assert(v >= 0 && v < (int) edges.size());
        return edges[v];
    }

    std::vector<Edge> &operator[](int v) {
        assert(v >= 0 && v < (int) edges.size());
        return edges[v];
    }
};

struct UnweightedEdge {
    int to;

    UnweightedEdge(int t) : to(t) {}
    
    explicit operator int() const {
        return to;
    }

    using Weight = int;
    Weight weight() const {
        return 1;
    }
};

template <typename T>
struct WeightedEdge {
    int to;
    T wt;

    WeightedEdge(int t, const T &w) : to(t), wt(w) {}

    explicit operator int() const {
        return to;
    }

    using Weight = T;
    Weight weight() const {
        return wt;
    }
};

#line 2 "graph/strongly_connected_components.hpp"

#line 4 "graph/strongly_connected_components.hpp"

template <typename G>
class StronglyConnectedComponents {    
    std::vector<int> comp_id;
    int comp_num;
    
public:
    StronglyConnectedComponents(const G &g) : comp_id(g.size(), -1), comp_num(0) {
        int now = 0;
        std::vector<int> vs;
        std::vector<int> ord(g.size(), -1);
        std::vector<int> low(g.size(), -1);
        
        const auto dfs = [&](const auto &dfs, int v) -> void {
            vs.push_back(v);
            ord[v] = now++;
            low[v] = ord[v];
            for (int u : g[v]) {
                if (comp_id[u] != -1) {
                    continue;
                }
                if (ord[u] == -1) {
                    dfs(dfs, u);
                }
                low[v] = std::min(low[v], low[u]);
            }
            if (low[v] == ord[v]) {
                while (true) {
                    int u = vs.back();
                    vs.pop_back();
                    comp_id[u] = comp_num;
                    if (u == v) {
                        break;
                    }
                }
                ++comp_num;
            }
        };
        
        for (int v = 0; v < (int) g.size(); ++v) {
            if (ord[v] == -1) {
                dfs(dfs, v);
            }
        }
        
        for (int v = 0; v < (int) g.size(); ++v) {
            comp_id[v] = comp_num - 1 - comp_id[v];
        }
    }
    
    int comps() const {
        return comp_num;
    }

    int operator[](int v) const {
        assert(v >= 0 && v < (int) comp_id.size());
        return comp_id[v];
    }

    std::vector<std::vector<int>> groups() const {
        std::vector<std::vector<int>> ret(comp_num);
        for (int v = 0; v < (int) comp_id.size(); ++v) {
            ret[comp_id[v]].push_back(v);
        }
        return ret;
    }
};

#line 8 "graph/test/scc.test.cpp"

int main() {
    i32 n, m;
    cin >> n >> m;
    Graph<i32> g(n);
    REP(e, m) {
        i32 u, v;
        cin >> u >> v;
        g.add_directed_edge(u, v);
    }
    StronglyConnectedComponents<Graph<i32>> scc(g);
    Vec<Vec<i32>> groups = scc.groups();
    cout << groups.size() << '\n';
    for (const Vec<i32> &group : groups) {
        cout << group.size();
        for (i32 v : group) {
            cout << ' ' << v;
        }
        cout << '\n';
    }
}
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