tests/SCC.test.cpp

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Last update: 2025-11-28 02:09:51+07:00
Problem: https://judge.yosupo.jp/problem/scc

Depends on

Code

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

#include "../misc/macros.h"
#include "../graph/SCC.h"

void solve() {
  int n, m;
  cin >> n >> m;
  vector<vi> g(n);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    g[u].eb(v);
  }
  SCC scc(g);
  cout << sz(scc.dag) << '\n';
  for (int i = 0; i < sz(scc.dag); ++i) {
    cout << sz(scc.belong(i)) << ' ';
    for (auto v : scc.belong(i)) cout << v << ' ';
    cout << '\n';
  }
}

int main() {
  solve();
}

#line 1 "tests/SCC.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/scc"

#line 1 "misc/macros.h"
// #pragma GCC optimize("Ofast,unroll-loops")       // unroll long, simple loops
// #pragma GCC target("avx2,fma")                   // vectorizing code
// #pragma GCC target("lzcnt,popcnt,abm,bmi,bmi2")  // for fast bitset operation

#include <bits/extc++.h>
#include <tr2/dynamic_bitset>

using namespace std;
using namespace __gnu_pbds;  // ordered_set, gp_hash_table
// using namespace __gnu_cxx; // rope

// for templates to work
#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
#define pb push_back
#define eb emplace_back
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;
using ld = long double;
using pii = pair<i32, i32>;
using vi = vector<i32>;

// fast map
const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash {  // customize hash function for gp_hash_table
  int operator()(int x) const { return x ^ RANDOM; }
};
gp_hash_table<int, int, chash> table;

/* ordered set
    find_by_order(k): returns an iterator to the k-th element (0-based)
    order_of_key(k): returns the number of elements in the set that are strictly less than k
*/
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

/*  rope
    rope <int> cur = v.substr(l, r - l + 1);
    v.erase(l, r - l + 1);
    v.insert(v.mutable_begin(), cur);
*/
#line 1 "graph/SCC.h"
template <class G>
struct SCC {
 public:
  vector<vi> dag;
  SCC(G& g) : g(g), used(sz(g), 0) { build(); }
  int operator[](int k) { return comp[k]; }
  vi& belong(int i) { return blng[i]; }

 private:
  const G& g;
  vector<vi> rg;
  vi comp, ord;
  vector<bool> used;
  vector<vi> blng;

  void dfs(int idx) {
    if (used[idx]) return;
    used[idx] = true;
    for (auto to : g[idx]) dfs(int(to));
    ord.eb(idx);
  }
  void rdfs(int idx, int cnt) {
    if (comp[idx] != -1) return;
    comp[idx] = cnt;
    for (int to : rg[idx]) rdfs(to, cnt);
  }
  void build() {
    for (int i = 0; i < sz(g); i++) dfs(i);
    reverse(all(ord));
    used.clear(), used.shrink_to_fit();
    comp.resize(sz(g), -1);
    rg.resize(sz(g));
    for (int i = 0; i < sz(g); i++) {
      for (auto e : g[i]) {
        rg[e].emplace_back(i);
      }
    }
    int ptr = 0;
    for (int i : ord)
      if (comp[i] == -1) rdfs(i, ptr), ptr++;
    rg.clear(), rg.shrink_to_fit();
    ord.clear(), ord.shrink_to_fit();
    dag.resize(ptr), blng.resize(ptr);
    for (int i = 0; i < (int) sz(g); i++) {
      blng[comp[i]].eb(i);
      for (auto& to : g[i]) {
        int x = comp[i], y = comp[to];
        if (x == y) continue;
        dag[x].eb(y);
      }
    }
  }
};
#line 5 "tests/SCC.test.cpp"

void solve() {
  int n, m;
  cin >> n >> m;
  vector<vi> g(n);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    g[u].eb(v);
  }
  SCC scc(g);
  cout << sz(scc.dag) << '\n';
  for (int i = 0; i < sz(scc.dag); ++i) {
    cout << sz(scc.belong(i)) << ' ';
    for (auto v : scc.belong(i)) cout << v << ' ';
    cout << '\n';
  }
}

int main() {
  solve();
}