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graph/test/scc.test.cpp
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- Last update: 2025-06-28 10:05:47+09:00
- Problem: https://judge.yosupo.jp/problem/scc
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Code
#define PROBLEM "https://judge.yosupo.jp/problem/scc"
#define FAST_IO
#include "../../graph/strongly_connected_components.hpp"
#include "../../template/template.hpp"
void solve() {
I32(n, m);
Graph<i32, true> g(n);
REP(i, m) {
I32(u, v);
g.add_edge(u, v);
}
g.build();
V<i32> comp = strongly_connected_components(g);
VV<i32> groups(n);
REP(i, n) { groups[comp[i]].push_back(i); }
while (groups.back().empty()) {
groups.pop_back();
}
cout << LEN(groups) << '\n';
for (const V<i32> &gr : groups) {
cout << LEN(gr);
for (i32 v : gr) {
cout << ' ' << v;
}
cout << '\n';
}
}
int main() {
i32 t = 1;
// cin >> t;
while (t--) {
solve();
}
}#line 1 "graph/test/scc.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"
#define FAST_IO
#line 2 "graph/graph.hpp"
#include <iostream>
#include <cassert>
#include <vector>
template <typename T>
struct Edge {
using W = T;
int from, to, id;
W weight;
Edge<T> rev() const {
return Edge<T>{to, from, id, weight};
}
};
template <typename T>
void debug(const Edge<T> &e) {
std::cerr << e.from << " -> " << e.to << " id = " << e.id << std::cerr << " weight = ";
debug(e.weight);
}
template <typename T = int, bool DIR = false>
class Graph {
public:
using E = Edge<T>;
using W = T;
static constexpr bool DIRECTED = DIR;
struct Adjacency {
using Iter = typename std::vector<E>::iterator;
Iter be, en;
Iter begin() const { return be; }
Iter end() const { return en; }
int size() const { return (int)std::distance(be, en); }
E &operator[](int idx) const { return be[idx]; }
};
struct ConstAdjacency {
using Iter = typename std::vector<E>::const_iterator;
Iter be, en;
Iter begin() const { return be; }
Iter end() const { return en; }
int size() const { return (int)std::distance(be, en); }
const E &operator[](int idx) const { return be[idx]; }
};
private:
int n, m;
std::vector<E> edges, csr;
std::vector<int> sep;
bool built;
public:
Graph(int n) : n(n), m(0), built(false) {}
int v() const { return n; }
int e() const { return m; }
int add_vertex() {
return n++;
}
void add_edge(int from, int to, W weight = 1) {
assert(0 <= from && from < n && 0 <= to && to < n);
edges.emplace_back(E{from, to, m++, weight});
}
void build() {
sep.assign(n + 1, 0);
csr.resize(DIRECTED ? m : 2 * m);
for (const E &e : edges) {
++sep[e.from + 1];
if (!DIRECTED) {
++sep[e.to + 1];
}
}
for (int i = 0; i < n; ++i) {
sep[i + 1] += sep[i];
}
std::vector<int> c = sep;
for (const E &e : edges) {
csr[c[e.from]++] = e;
if (!DIRECTED) {
csr[c[e.to]++] = e.rev();
}
}
built = true;
}
Adjacency operator[](int v) {
assert(built && 0 <= v && v < n);
return Adjacency{csr.begin() + sep[v], csr.begin() + sep[v + 1]};
}
ConstAdjacency operator[](int v) const {
assert(built && 0 <= v && v < n);
return ConstAdjacency{csr.begin() + sep[v], csr.begin() + sep[v + 1]};
}
};
#line 3 "graph/strongly_connected_components.hpp"
template <typename T>
std::vector<int> strongly_connected_components(const Graph<T, true> &g) {
std::vector<int> comp(g.v(), -1);
int t = 0, cc = 0;
std::vector<int> vs, ord(g.v(), -1), low(g.v(), -1);
auto dfs = [&](auto dfs, int v) -> void {
vs.push_back(v);
ord[v] = low[v] = t++;
for (const Edge<T> &e : g[v]) {
if (comp[e.to] != -1) {
continue;
}
if (ord[e.to] == -1) {
dfs(dfs, e.to);
}
if (low[e.to] < low[v]) {
low[v] = low[e.to];
}
}
if (low[v] == ord[v]) {
while (comp[v] == -1) {
int u = vs.back();
vs.pop_back();
comp[u] = cc;
}
++cc;
}
};
for (int i = 0; i < g.v(); ++i) {
if (ord[i] == -1) {
dfs(dfs, i);
}
}
for (int i = 0; i < g.v(); ++i) {
comp[i] = cc - 1 - comp[i];
}
return comp;
}
#line 2 "template/template.hpp"
#include <bits/stdc++.h>
#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 PER2(i, n) for (i32 i = (i32)(n)-1; i >= 0; --i)
#define PER3(i, m, n) for (i32 i = (i32)(n)-1; i >= (i32)(m); --i)
#define PER(...) OVERRIDE(__VA_ARGS__, PER3, PER2)(__VA_ARGS__)
#define ALL(x) begin(x), end(x)
#define LEN(x) (i32)(x.size())
using namespace std;
using u32 = unsigned int;
using u64 = unsigned long long;
using i32 = signed int;
using i64 = signed long long;
using f64 = double;
using f80 = long double;
using pi = pair<i32, i32>;
using pl = pair<i64, i64>;
template <typename T>
using V = vector<T>;
template <typename T>
using VV = V<V<T>>;
template <typename T>
using VVV = V<V<V<T>>>;
template <typename T>
using VVVV = V<V<V<V<T>>>>;
template <typename T>
using PQR = priority_queue<T, V<T>, greater<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;
}
template <typename T>
i32 lob(const V<T> &arr, const T &v) {
return (i32)(lower_bound(ALL(arr), v) - arr.begin());
}
template <typename T>
i32 upb(const V<T> &arr, const T &v) {
return (i32)(upper_bound(ALL(arr), v) - arr.begin());
}
template <typename T>
V<i32> argsort(const V<T> &arr) {
V<i32> ret(arr.size());
iota(ALL(ret), 0);
sort(ALL(ret), [&](i32 i, i32 j) -> bool {
if (arr[i] == arr[j]) {
return i < j;
} else {
return arr[i] < arr[j];
}
});
return ret;
}
#ifdef INT128
using u128 = __uint128_t;
using i128 = __int128_t;
#endif
[[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;
void scan(char &x) { cin >> x; }
void scan(u32 &x) { cin >> x; }
void scan(u64 &x) { cin >> x; }
void scan(i32 &x) { cin >> x; }
void scan(i64 &x) { cin >> x; }
void scan(f64 &x) { cin >> x; }
void scan(string &x) { cin >> x; }
template <typename T>
void scan(V<T> &x) {
for (T &ele : x) {
scan(ele);
}
}
void read() {}
template <typename Head, typename... Tail>
void read(Head &head, Tail &...tail) {
scan(head);
read(tail...);
}
#define CHAR(...) \
char __VA_ARGS__; \
read(__VA_ARGS__);
#define U32(...) \
u32 __VA_ARGS__; \
read(__VA_ARGS__);
#define U64(...) \
u64 __VA_ARGS__; \
read(__VA_ARGS__);
#define I32(...) \
i32 __VA_ARGS__; \
read(__VA_ARGS__);
#define I64(...) \
i64 __VA_ARGS__; \
read(__VA_ARGS__);
#define F64(...) \
f64 __VA_ARGS__; \
read(__VA_ARGS__);
#define STR(...) \
string __VA_ARGS__; \
read(__VA_ARGS__);
#define VEC(type, name, size) \
V<type> name(size); \
read(name);
#define VVEC(type, name, size1, size2) \
VV<type> name(size1, V<type>(size2)); \
read(name);
#line 5 "graph/test/scc.test.cpp"
void solve() {
I32(n, m);
Graph<i32, true> g(n);
REP(i, m) {
I32(u, v);
g.add_edge(u, v);
}
g.build();
V<i32> comp = strongly_connected_components(g);
VV<i32> groups(n);
REP(i, n) { groups[comp[i]].push_back(i); }
while (groups.back().empty()) {
groups.pop_back();
}
cout << LEN(groups) << '\n';
for (const V<i32> &gr : groups) {
cout << LEN(gr);
for (i32 v : gr) {
cout << ' ' << v;
}
cout << '\n';
}
}
int main() {
i32 t = 1;
// cin >> t;
while (t--) {
solve();
}
}