結果

問題 No.2677 Minmax Independent Set
ユーザー ei1333333
提出日時 2024-03-15 21:55:43
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 232 ms / 2,000 ms
コード長 4,205 bytes
コンパイル時間 4,312 ms
コンパイル使用メモリ 260,144 KB
最終ジャッジ日時 2025-02-20 05:03:31
ジャッジサーバーID
（参考情報） 		judge1 / judge5
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ファイルパターン 結果
sample AC * 3
other AC * 61
権限があれば一括ダウンロードができます

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>
using namespace std;
using int64 = long long;
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 1 "graph/tree/rerooting.hpp"
template< typename sum_t, typename key_t >
struct ReRooting {
  struct Edge {
    int to;
    key_t data;
    sum_t dp, ndp;
  };
  using F = function< sum_t(sum_t, sum_t) >;
  using G = function< sum_t(sum_t, key_t) >;
  vector< vector< Edge > > g;
  const F f;
  const G gg;
  const sum_t ident;
  vector< sum_t > subdp, dp;
  ReRooting(int V, const F f, const G g, const sum_t &ident)
      : g(V), f(f), gg(g), ident(ident), subdp(V, ident), dp(V, ident) {}
  void add_edge(int u, int v, const key_t &d) {
    g[u].emplace_back((Edge) {v, d, ident, ident});
    g[v].emplace_back((Edge) {u, d, ident, ident});
  }
  void add_edge_bi(int u, int v, const key_t &d, const key_t &e) {
    g[u].emplace_back((Edge) {v, d, ident, ident});
    g[v].emplace_back((Edge) {u, e, ident, ident});
  }
  void dfs_sub(int idx, int par) {
    for(auto &e : g[idx]) {
      if(e.to == par) continue;
      dfs_sub(e.to, idx);
      subdp[idx] = f(subdp[idx], gg(subdp[e.to], e.data));
    }
  }
  void dfs_all(int idx, int par, const sum_t &top) {
    sum_t buff{ident};
    for(int i = 0; i < (int) g[idx].size(); i++) {
      auto &e = g[idx][i];
      e.ndp = buff;
      e.dp = gg(par == e.to ? top : subdp[e.to], e.data);
      buff = f(buff, e.dp);
    }
    dp[idx] = buff;
    buff = ident;
    for(int i = (int) g[idx].size() - 1; i >= 0; i--) {
      auto &e = g[idx][i];
      if(e.to != par) dfs_all(e.to, idx, f(e.ndp, buff));
      e.ndp = f(e.ndp, buff);
      buff = f(buff, e.dp);
    }
  }
  vector< sum_t > build() {
    dfs_sub(0, -1);
    dfs_all(0, -1, ident);
    return dp;
  }
};
int main() {
  using pi = pair< int, int >;
  auto f = [](const pi& a, const pi& b) {
    return pi(a.first + b.first, a.second + b.second);
  };
  auto g = [](const pi& a, bool x) {
    return pi(max(a.first, a.second + 1), a.first);
  };
  int N;
  cin >> N;
  ReRooting< pi, bool > dp(N, f, g, pi());
  for(int i = 1; i < N; i++) {
    int u, v;
    cin >> u >> v;
    --u, --v;
    dp.add_edge(u, v, false);
  }
  auto ans = dp.build();
  int ret = inf;
  for(int i = 0; i < N; i++) {
    chmin(ret, ans[i].second + 1);
  }
  cout << ret << endl;
}
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