C++ Library for Competitive Programming
/*
* @title グラフ/強連結成分分解
*
* verification-helper: PROBLEM https://judge.yosupo.jp/problem/scc
*/
#include <iostream>
#include <vector>
#include "emthrm/graph/edge.hpp"
#include "emthrm/graph/strongly_connected_components.hpp"
int main() {
int n, m;
std::cin >> n >> m;
std::vector<std::vector<emthrm::Edge<bool>>> graph(n);
while (m--) {
int a, b;
std::cin >> a >> b;
graph[a].emplace_back(a, b);
}
const std::vector<std::vector<int>> ans =
emthrm::StronglyConnectedComponents<bool, true>(graph).vertices;
const int k = ans.size();
std::cout << k << '\n';
for (int i = 0; i < k; ++i) {
const int l = ans[i].size();
std::cout << l << ' ';
for (int j = 0; j < l; ++j) {
std::cout << ans[i][j] << " \n"[j + 1 == l];
}
}
return 0;
}
#line 1 "test/graph/strongly_connected_components.test.cpp"
/*
* @title グラフ/強連結成分分解
*
* verification-helper: PROBLEM https://judge.yosupo.jp/problem/scc
*/
#include <iostream>
#include <vector>
#line 1 "include/emthrm/graph/edge.hpp"
/**
* @title 辺
*/
#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_
#include <compare>
namespace emthrm {
template <typename CostType>
struct Edge {
CostType cost;
int src, dst;
explicit Edge(const int src, const int dst, const CostType cost = 0)
: cost(cost), src(src), dst(dst) {}
auto operator<=>(const Edge& x) const = default;
};
} // namespace emthrm
#endif // EMTHRM_GRAPH_EDGE_HPP_
#line 1 "include/emthrm/graph/strongly_connected_components.hpp"
// #include <algorithm>
#include <ranges>
#line 7 "include/emthrm/graph/strongly_connected_components.hpp"
#line 1 "include/emthrm/graph/edge.hpp"
/**
* @title 辺
*/
#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_
#include <compare>
namespace emthrm {
template <typename CostType>
struct Edge {
CostType cost;
int src, dst;
explicit Edge(const int src, const int dst, const CostType cost = 0)
: cost(cost), src(src), dst(dst) {}
auto operator<=>(const Edge& x) const = default;
};
} // namespace emthrm
#endif // EMTHRM_GRAPH_EDGE_HPP_
#line 9 "include/emthrm/graph/strongly_connected_components.hpp"
namespace emthrm {
template <typename CostType, bool IS_FULL_VER = false>
struct StronglyConnectedComponents {
std::vector<int> id;
std::vector<std::vector<int>> vertices;
std::vector<std::vector<Edge<CostType>>> g;
explicit StronglyConnectedComponents(
const std::vector<std::vector<Edge<CostType>>>& graph)
: n(graph.size()), is_used(n, false), graph(graph), rgraph(n) {
for (int i = 0; i < n; ++i) {
if (!is_used[i]) dfs(i);
}
id.assign(n, -1);
order.reserve(n);
for (int i = 0; i < n; ++i) {
for (const Edge<CostType>& e : graph[i]) {
rgraph[e.dst].emplace_back(e.dst, e.src, e.cost);
}
}
int m = 0;
for (int i = n - 1; i >= 0; --i) {
if (id[order[i]] == -1) {
if constexpr (IS_FULL_VER) vertices.emplace_back();
rdfs(order[i], m++);
}
}
g.resize(m);
for (int i = 0; i < n; ++i) {
for (const Edge<CostType>& e : graph[i]) {
if (id[i] != id[e.dst]) g[id[i]].emplace_back(id[i], id[e.dst], e.cost);
}
}
// if constexpr (IS_FULL_VER) {
// for (int i = 0; i < m; ++i) {
// std::sort(vertices[i].begin(), vertices[i].end());
// }
// }
}
private:
const int n;
std::vector<bool> is_used;
std::vector<int> order;
const std::vector<std::vector<Edge<CostType>>> graph;
std::vector<std::vector<Edge<CostType>>> rgraph;
void dfs(const int ver) {
is_used[ver] = true;
for (const int e : graph[ver]
| std::views::transform(&Edge<CostType>::dst)) {
if (!is_used[e]) dfs(e);
}
order.emplace_back(ver);
}
void rdfs(const int ver, const int m) {
id[ver] = m;
if constexpr (IS_FULL_VER) vertices.back().emplace_back(ver);
for (const int e : rgraph[ver]
| std::views::transform(&Edge<CostType>::dst)) {
if (id[e] == -1) rdfs(e, m);
}
}
};
} // namespace emthrm
#line 12 "test/graph/strongly_connected_components.test.cpp"
int main() {
int n, m;
std::cin >> n >> m;
std::vector<std::vector<emthrm::Edge<bool>>> graph(n);
while (m--) {
int a, b;
std::cin >> a >> b;
graph[a].emplace_back(a, b);
}
const std::vector<std::vector<int>> ans =
emthrm::StronglyConnectedComponents<bool, true>(graph).vertices;
const int k = ans.size();
std::cout << k << '\n';
for (int i = 0; i < k; ++i) {
const int l = ans[i].size();
std::cout << l << ' ';
for (int j = 0; j < l; ++j) {
std::cout << ans[i][j] << " \n"[j + 1 == l];
}
}
return 0;
}