tests/Maximum_Independent_Set.test.cpp

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Last update: 2025-11-28 13:07:52+07:00
Problem: https://judge.yosupo.jp/problem/maximum_independent_set

Depends on

Code

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

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

signed main() {
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
  int n, m;
  cin >> n >> m;
  vector<bs> adj(n, bs(n));
  for (int i = 0; i < n; ++i) {
    adj[i].set();     // Full 1
    adj[i][i] = 0;    // QUAN TRỌNG: Tắt self-loop
  }
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    adj[u][v] = adj[v][u] = 0;
  }
  bs P(n), R(n), sol(n); 
  u32 ans=0; P.set(); 
  MaxClique(adj, P, R, sol, ans);
  cout << ans << '\n';
  for (int i = sol.find_first(); i < sz(sol); i = sol.find_next(i)) {
    cout << i << ' ';
  }
}

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

#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/Cliques.h"
using bs = tr2::dynamic_bitset<uint64_t>;

// Usage: bs P(n), X(n), R(n); P.set(); EnumClique(g, [&](bs& c){...}, P, X, R);
template <class F>
void EnumClique(vector<bs>& g, F f, bs P, bs X, bs R) {
  f(R); 
  if (P.none() && X.none()) return;
  // if only need to find all maximal cliques
  // auto q = (P | X).find_first();
  // auto cands = P & ~g[q]; // then trav through cands
  for (auto i = P.find_first(); i < sz(P); i = P.find_next(i)) {
    R[i] = 1;
    EnumClique(g, f, P & g[i], X & g[i], R);
    R[i] = 0, P[i] = 0, X[i] = 1;
  }
}

// Usage: bs P(n), R(n), sol; u64 ans=0; P.set(); MaxClique(g, P, R, sol, ans);
void MaxClique(vector<bs>& g, bs P, bs R, bs& sol, u32& res) {
  if (R.count() + P.count() <= res) return;
  if (P.none()) { res = R.count(), sol = R; return; }
  auto q = P.find_first(), max_k = u64(0);
  for (auto i = q; i < sz(P); i = P.find_next(i)) {
    auto k = (P & g[i]).count();
    if (k > max_k) max_k = k, q = i;
  }
  bs cands = P & ~g[q];
  for (auto i = cands.find_first(); i < sz(cands); i = cands.find_next(i)) {
    R[i] = 1, MaxClique(g, P & g[i], R, sol, res);
    R[i] = P[i] = 0;
  }
}
#line 5 "tests/Maximum_Independent_Set.test.cpp"

signed main() {
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
  int n, m;
  cin >> n >> m;
  vector<bs> adj(n, bs(n));
  for (int i = 0; i < n; ++i) {
    adj[i].set();     // Full 1
    adj[i][i] = 0;    // QUAN TRỌNG: Tắt self-loop
  }
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    adj[u][v] = adj[v][u] = 0;
  }
  bs P(n), R(n), sol(n); 
  u32 ans=0; P.set(); 
  MaxClique(adj, P, R, sol, ans);
  cout << ans << '\n';
  for (int i = sol.find_first(); i < sz(sol); i = sol.find_next(i)) {
    cout << i << ' ';
  }
}