Luzhiled's Library

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:x: test/verify/yukicoder-1254.test.cpp

Depends on

Code

#define PROBLEM "https://yukicoder.me/problems/no/1254"

#include "../../template/template.hpp"

#include "../../graph/others/namori-graph.hpp"

int main() {
  int N;
  cin >> N;
  NamoriGraph< int > g(N);
  g.read(N);
  g.build();
  vector< int > ans;
  for(auto &e : g.loop_edges) {
    ans.emplace_back(e.idx + 1);
  }
  sort(begin(ans), end(ans));
  cout << ans.size() << "\n";
  cout << ans << "\n";
}
#line 1 "test/verify/yukicoder-1254.test.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/1254"

#line 1 "template/template.hpp"
#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;

template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  explicit FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};
 
template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}
#line 4 "test/verify/yukicoder-1254.test.cpp"

#line 2 "graph/others/namori-graph.hpp"

#line 2 "graph/graph-template.hpp"

/**
 * @brief Graph Template(グラフテンプレート)
 */
template< typename T = int >
struct Edge {
  int from, to;
  T cost;
  int idx;

  Edge() = default;

  Edge(int from, int to, T cost = 1, int idx = -1) : from(from), to(to), cost(cost), idx(idx) {}

  operator int() const { return to; }
};

template< typename T = int >
struct Graph {
  vector< vector< Edge< T > > > g;
  int es;

  Graph() = default;

  explicit Graph(int n) : g(n), es(0) {}

  size_t size() const {
    return g.size();
  }

  void add_directed_edge(int from, int to, T cost = 1) {
    g[from].emplace_back(from, to, cost, es++);
  }

  void add_edge(int from, int to, T cost = 1) {
    g[from].emplace_back(from, to, cost, es);
    g[to].emplace_back(to, from, cost, es++);
  }

  void read(int M, int padding = -1, bool weighted = false, bool directed = false) {
    for(int i = 0; i < M; i++) {
      int a, b;
      cin >> a >> b;
      a += padding;
      b += padding;
      T c = T(1);
      if(weighted) cin >> c;
      if(directed) add_directed_edge(a, b, c);
      else add_edge(a, b, c);
    }
  }

  inline vector< Edge< T > > &operator[](const int &k) {
    return g[k];
  }

  inline const vector< Edge< T > > &operator[](const int &k) const {
    return g[k];
  }
};

template< typename T = int >
using Edges = vector< Edge< T > >;
#line 4 "graph/others/namori-graph.hpp"

/**
 * @brief Namori Graph
 * @docs docs/namori-graph.md
 */
template< typename T = int >
struct NamoriGraph : Graph< T > {
public:
  using Graph< T >::Graph;
  using Graph< T >::g;

  vector< Graph< T > > forest;
  Edges< T > loop_edges;

  struct Info {
    int tree_id, id;
  };

  Info operator[](const int &k) const {
    return (Info) {mark_id[k], id[k]};
  }

  int inv(int tree_id, int k) {
    return iv[tree_id][k];
  }

  void build() {
    int n = (int) g.size();
    vector< int > deg(n), used(n);
    queue< int > que;
    for(int i = 0; i < n; i++) {
      deg[i] = (int) g[i].size();
      if(deg[i] == 1) {
        que.emplace(i);
        used[i] = true;
      }
    }
    while(not que.empty()) {
      int idx = que.front();
      que.pop();
      for(auto &e : g[idx]) {
        if(used[e.to]) {
          continue;
        }
        --deg[e.to];
        if(deg[e.to] == 1) {
          que.emplace(e.to);
          used[e.to] = true;
        }
      }
    }
    int mx = 0;
    for(auto &edges : g) {
      for(auto &e : edges) mx = max(mx, e.idx);
    }
    vector< int > edge_used(mx + 1);
    vector< int > loop;
    for(int v = 0; v < n; v++) {
      if(!used[v]) {
        for(bool update = true; update;) {
          update = false;
          loop.emplace_back(v);
          for(auto &e : g[v]) {
            if(used[e.to] or edge_used[e.idx]) {
              continue;
            }
            edge_used[e.idx] = true;
            loop_edges.emplace_back(v, e.to, e.cost, e.idx);
            v = e.to;
            update = true;
            break;
          }
        }
        break;
      }
    }
    loop.pop_back();
    mark_id.resize(n);
    id.resize(n);
    for(int i = 0; i < (int) loop.size(); i++) {
      int pre = loop[(i + loop.size() - 1) % loop.size()];
      int nxt = loop[(i + 1) % loop.size()];
      int sz = 0;
      mark_id[loop[i]] = i;
      iv.emplace_back();
      id[loop[i]] = sz++;
      iv.back().emplace_back(loop[i]);
      for(auto &e : g[loop[i]]) {
        if(e.to != pre and e.to != nxt) {
          mark_dfs(e.to, loop[i], i, sz);
        }
      }
      Graph< T > tree(sz);
      for(auto &e : g[loop[i]]) {
        if(e.to != pre and e.to != nxt) {
          tree.g[id[loop[i]]].emplace_back(id[loop[i]], id[e.to], e.cost, e.idx);
          tree.g[id[e.to]].emplace_back(id[e.to], id[loop[i]], e.cost, e.idx);
          build_dfs(e.to, loop[i], tree);
        }
      }
      forest.emplace_back(tree);
    }
  }

private:
  vector< vector< int > > iv;
  vector< int > mark_id, id;

  void mark_dfs(int idx, int par, int k, int &l) {
    mark_id[idx] = k;
    id[idx] = l++;
    iv.back().emplace_back(idx);
    for(auto &e : g[idx]) {
      if(e.to != par) {
        mark_dfs(e.to, idx, k, l);
      }
    }
  }

  void build_dfs(int idx, int par, Graph< T > &tree) {
    for(auto &e : g[idx]) {
      if(e.to != par) {
        tree.g[id[idx]].emplace_back(id[idx], id[e.to], e.cost, e.idx);
        tree.g[id[e.to]].emplace_back(id[e.to], id[idx], e.cost, e.idx);
        build_dfs(e.to, idx, tree);
      }
    }
  }
};
#line 6 "test/verify/yukicoder-1254.test.cpp"

int main() {
  int N;
  cin >> N;
  NamoriGraph< int > g(N);
  g.read(N);
  g.build();
  vector< int > ans;
  for(auto &e : g.loop_edges) {
    ans.emplace_back(e.idx + 1);
  }
  sort(begin(ans), end(ans));
  cout << ans.size() << "\n";
  cout << ans << "\n";
}
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