tests/General_Matching.test.cpp

View this file on GitHub
Last update: 2025-11-28 02:09:51+07:00
Problem: https://judge.yosupo.jp/problem/general_matching

Depends on

Code

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

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

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<vi> graph(n);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    graph[u].pb(v), graph[v].pb(u);
  }
  auto match = GeneralMatching(graph);
  vector<pii> mate;
  for (int i = 0; i < n; ++i) {
    if (i < match[i]) mate.pb({i, match[i]});
  }
  cout << sz(mate) << '\n';
  for (auto [u, v] : mate) cout << u << ' ' << v << '\n';
}

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

#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/GeneralMatching.h"
vi GeneralMatching(vector<vi>& graph) {
  int n = graph.size(), timer = -1;
  vi mate(n, -1), label(n), parent(n), orig(n), aux(n, -1), q;
  auto lca = [&](int x, int y) {
    for (timer++;; swap(x, y)) {
      if (x == -1) continue;
      if (aux[x] == timer) return x;
      aux[x] = timer;
      x = (mate[x] == -1 ? -1 : orig[parent[mate[x]]]);
    }
  };
  auto blossom = [&](int v, int w, int a) {
    while (orig[v] != a) {
      parent[v] = w;
      w = mate[v];
      if (label[w] == 1) label[w] = 0, q.push_back(w);
      orig[v] = orig[w] = a;
      v = parent[w];
    }
  };
  auto augment = [&](int v) {
    while (v != -1) {
      int pv = parent[v], nv = mate[pv];
      mate[v] = pv;
      mate[pv] = v;
      v = nv;
    }
  };
  auto bfs = [&](int root) {
    fill(label.begin(), label.end(), -1);
    iota(orig.begin(), orig.end(), 0);
    q.clear();
    label[root] = 0;
    q.push_back(root);
    for (int i = 0; i < (int) q.size(); ++i) {
      int v = q[i];
      for (auto x : graph[v]) {
        if (label[x] == -1) {
          label[x] = 1;
          parent[x] = v;
          if (mate[x] == -1)
            return augment(x), 1;
          label[mate[x]] = 0;
          q.push_back(mate[x]);
        } else if (label[x] == 0 && orig[v] != orig[x]) {
          int a = lca(orig[v], orig[x]);
          blossom(x, v, a);
          blossom(v, x, a);
        }
      }
    }
    return 0;
  };
  // Time halves if you start with (any) maximal matching.
  for (int i = 0; i < n; i++)
    if (mate[i] == -1)
      bfs(i);
  return mate;
}
#line 5 "tests/General_Matching.test.cpp"

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<vi> graph(n);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    graph[u].pb(v), graph[v].pb(u);
  }
  auto match = GeneralMatching(graph);
  vector<pii> mate;
  for (int i = 0; i < n; ++i) {
    if (i < match[i]) mate.pb({i, match[i]});
  }
  cout << sz(mate) << '\n';
  for (auto [u, v] : mate) cout << u << ' ' << v << '\n';
}