結果

問題 No.8107 Listening
ユーザー 👑 binap
提出日時 2024-04-01 21:49:36
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 4,439 bytes
コンパイル時間 5,055 ms
コンパイル使用メモリ 270,756 KB
最終ジャッジ日時 2025-02-20 19:06:43
ジャッジサーバーID
（参考情報） 		judge3 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2 WA * 1
other WA * 16 TLE * 3 -- * 21
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ソースコード

diff #
プレゼンテーションモードにする

#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;
ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const dynamic_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return 
    os;}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); 
    return os;}
template<typename T> void chmin(T& a, T b){a = min(a, b);}
template<typename T> void chmax(T& a, T b){a = max(a, b);}
//https://ei1333.github.io/library/graph/flow/gabow-edmonds.hpp.html
// https://qiita.com/Kutimoti_T/items/5b579773e0a24d650bdf
/**
 * @brief Gabow Edmonds(一般グラフの最大マッチング)
 * @docs docs/gabow-edmonds.md
 */
struct GabowEdmonds {
  struct edge {
    int to, idx;
  };
  vector< vector< edge > > g;
  vector< pair< int, int > > edges;
  vector< int > mate, label, first;
  queue< int > que;
  GabowEdmonds(int n) : g(n + 1), mate(n + 1), label(n + 1, -1), first(n + 1) {}
  void add_edge(int u, int v) {
    ++u, ++v;
    g[u].push_back((edge) {v, (int) (edges.size() + g.size())});
    g[v].push_back((edge) {u, (int) (edges.size() + g.size())});
    edges.emplace_back(u, v);
  }
  int find(int x) {
    if(label[first[x]] < 0) return first[x];
    first[x] = find(first[x]);
    return first[x];
  }
  void rematch(int v, int w) {
    int t = mate[v];
    mate[v] = w;
    if(mate[t] != v) return;
    if(label[v] < (int)g.size()) {
      mate[t] = label[v];
      rematch(label[v], t);
    } else {
      int x = edges[label[v] - g.size()].first;
      int y = edges[label[v] - g.size()].second;
      rematch(x, y);
      rematch(y, x);
    }
  }
  void assign_label(int x, int y, int num) {
    int r = find(x);
    int s = find(y);
    int join = 0;
    if(r == s) return;
    label[r] = -num;
    label[s] = -num;
    while(true) {
      if(s != 0) swap(r, s);
      r = find(label[mate[r]]);
      if(label[r] == -num) {
        join = r;
        break;
      }
      label[r] = -num;
    }
    int v = first[x];
    while(v != join) {
      que.push(v);
      label[v] = num;
      first[v] = join;
      v = first[label[mate[v]]];
    }
    v = first[y];
    while(v != join) {
      que.push(v);
      label[v] = num;
      first[v] = join;
      v = first[label[mate[v]]];
    }
  }
  bool augment_check(int u) {
    que = queue< int >();
    first[u] = 0;
    label[u] = 0;
    que.push(u);
    while(!que.empty()) {
      int x = que.front();
      que.pop();
      for(auto e : g[x]) {
        int y = e.to;
        if(mate[y] == 0 && y != u) {
          mate[y] = x;
          rematch(x, y);
          return true;
        } else if(label[y] >= 0) {
          assign_label(x, y, e.idx);
        } else if(label[mate[y]] < 0) {
          label[mate[y]] = x;
          first[mate[y]] = y;
          que.push(mate[y]);
        }
      }
    }
    return false;
  }
  vector< pair< int, int > > max_matching() {
    for(int i = 1; i < (int)g.size(); i++) {
      if(mate[i] != 0) continue;
      if(augment_check(i)) label.assign(g.size(), -1);
    }
    vector< pair< int, int > > ret;
    for(int i = 1; i < (int)g.size(); i++) {
      if(i < mate[i]) ret.emplace_back(i - 1, mate[i] - 1);
    }
    return ret;
  }
};
int main() {
  int N, M;
  cin >> N >> M;
  GabowEdmonds flow(N);
  map<pair<int, int>, int> ma;
  for(int i = 0; i < M; i++) {
    int a, b;
    cin >> a >> b;
    a--; b--;
    ma[make_pair(a, b)] = i;
    flow.add_edge(a, b);
  }
  auto ret = flow.max_matching();
  cout << ret.size() << endl;
  for(auto &p : ret) cout << ma[p] + 1 << endl;
}
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