結果

問題 No.1976 Cut then Connect
ユーザー miyo2580
提出日時 2023-12-07 15:21:20
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 252 ms / 2,000 ms
コード長 6,841 bytes
コンパイル時間 1,992 ms
コンパイル使用メモリ 190,836 KB
実行使用メモリ 27,396 KB
最終ジャッジ日時 2024-09-27 02:10:59
合計ジャッジ時間 6,262 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge5
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
other AC * 31
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp: In lambda function:
main.cpp:222:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  222 |       auto[a,b,c,d]=x;
      |           ^
main.cpp:223:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  223 |       auto[A,B,C,D]=y;
      |           ^
main.cpp: In lambda function:
main.cpp:250:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  250 |       auto[a,b,c,d]=x;
      |           ^

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>
using namespace std;
#define repd(i,a,b) for (ll i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
typedef long long ll;
typedef pair<ll,ll> P;
typedef vector<ll> vec;
using Graph = vector<vector<ll>>;
const long long INF = 1LL<<60;
const long long MOD = 1000000007;
//https://nyaannyaan.github.io/library/graph/graph-template.hpp
template <typename T>
struct edge {
  int src, to;
  T cost;
  edge(int _to, T _cost) : src(-1), to(_to), cost(_cost) {}
  edge(int _src, int _to, T _cost) : src(_src), to(_to), cost(_cost) {}
  edge &operator=(const int &x) {
    to = x;
    return *this;
  }
  operator int() const { return to; }
};
template <typename T>
using Edges = vector<edge<T>>;
template <typename T>
using WeightedGraph = vector<Edges<T>>;
using UnweightedGraph = vector<vector<int>>;
// Input of (Unweighted) Graph
UnweightedGraph graph(int N, int M = -1, bool is_directed = false,
                      bool is_1origin = true) {
  UnweightedGraph g(N);
  if (M == -1) M = N - 1;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    if (is_1origin) x--, y--;
    g[x].push_back(y);
    if (!is_directed) g[y].push_back(x);
  }
  return g;
}
// Input of Weighted Graph
template <typename T>
WeightedGraph<T> wgraph(int N, int M = -1, bool is_directed = false,
                        bool is_1origin = true) {
  WeightedGraph<T> g(N);
  if (M == -1) M = N - 1;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    cin >> c;
    if (is_1origin) x--, y--;
    g[x].emplace_back(x, y, c);
    if (!is_directed) g[y].emplace_back(y, x, c);
  }
  return g;
}
// Input of Edges
template <typename T>
Edges<T> esgraph(int N, int M, int is_weighted = true, bool is_1origin = true) {
  Edges<T> es;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    if (is_weighted)
      cin >> c;
    else
      c = 1;
    if (is_1origin) x--, y--;
    es.emplace_back(x, y, c);
  }
  return es;
}
// Input of Adjacency Matrix
template <typename T>
vector<vector<T>> adjgraph(int N, int M, T INF, int is_weighted = true,
                           bool is_directed = false, bool is_1origin = true) {
  vector<vector<T>> d(N, vector<T>(N, INF));
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    if (is_weighted)
      cin >> c;
    else
      c = 1;
    if (is_1origin) x--, y--;
    d[x][y] = c;
    if (!is_directed) d[y][x] = c;
  }
  return d;
}
/**
 * @brief グラフテンプレート
 * @docs docs/graph/graph-template.md
 */
//https://nyaannyaan.github.io/library/tree/rerooting.hpp
// Rerooting
// f1(c1, c2) ... merge value of child node
// f2(memo[i], chd, par) ... return value from child node to parent node
// memo[i] ... result of subtree rooted i
// dp[i] ... result of tree rooted i
template <typename T, typename G, typename F1, typename F2>
struct Rerooting {
  const G &g;
  const F1 f1;
  const F2 f2;
  vector<T> memo, dp;
  T I;
  Rerooting(const G &_g, const F1 _f1, const F2 _f2, const T &I_)
      : g(_g), f1(_f1), f2(_f2), memo(g.size(), I_), dp(g.size(), I_), I(I_) {
    dfs(0, -1);
    efs(0, -1, I);
  }
  const T &operator[](int i) const { return dp[i]; }
  void dfs(int cur, int par) {
    for (auto &dst : g[cur]) {
      if (dst == par) continue;
      dfs(dst, cur);
      memo[cur] = f1(memo[cur], f2(memo[dst], dst, cur));
    }
  }
  void efs(int cur, int par, const T &pval) {
    // get cumulative sum
    vector<T> buf;
    for (auto dst : g[cur]) {
      if (dst == par) continue;
      buf.push_back(f2(memo[dst], dst, cur));
    }
    vector<T> head(buf.size() + 1), tail(buf.size() + 1);
    head[0] = tail[buf.size()] = I;
    for (int i = 0; i < (int)buf.size(); i++) head[i + 1] = f1(head[i], buf[i]);
    for (int i = (int)buf.size() - 1; i >= 0; i--)
      tail[i] = f1(tail[i + 1], buf[i]);
    // update
    dp[cur] = par == -1 ? head.back() : f1(pval, head.back());
    // propagate
    int idx = 0;
    for (auto &dst : g[cur]) {
      if (dst == par) continue;
      efs(dst, cur, f2(f1(pval, f1(head[idx], tail[idx + 1])), cur, dst));
      idx++;
    }
  }
};
/**
 * @brief Rerooting(全方位木DP)
 * @docs docs/tree/rerooting.md
 */
// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
using F=tuple<ll,ll,ll,ll>;
int main()
{  
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n;
    cin>>n;
    auto g=graph(n,n-1,0,1);
    auto f1=[&](F x,F y){
      auto[a,b,c,d]=x;
      auto[A,B,C,D]=y;
      chmax(a,A);
      if(d==0&&D==0){
        c=B;
      }
      else if(d==0&&D==1){
        chmax(C,b);
        b=B;
        c=C;
      }
      else if(d==1&&D==0){
        chmax(c,B);
      }
      else{
        if(b<B){
          c=max(b,C);
          b=B;
        }
        else{
          chmax(c,B);
        }
      }
      if(b<c)swap(b,c);
      return F(a,b,c,1);
    };
    map<P,ll> mp;
    auto f2=[&](F x,ll ch,ll pa){
      auto[a,b,c,d]=x;
      chmax(a,b+c);
      mp[{ch,pa}]=a;
      b++;
      if(c>=1)c++;
      d=0;
      return F(a,b,c,d);
    };
    ll ans=INF;
    Rerooting<F,decltype(g),decltype(f1),decltype(f2)> dp(g,f1,f2,F(0,0,0,0));
    rep(i,n){
      for(ll ni:g[i]){
        if(i>ni)continue;
        ll x=mp[{i,ni}];
        ll y=mp[{ni,i}];
        ll now=0;
        chmax(now,x);
        chmax(now,y);
        chmax(now,(x+1)/2+(y+1)/2+1);
        chmin(ans,now);
      }
    }
    cout<<ans<<endl;
    return 0;
}
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