結果

問題 No.3206 う　し　た　ウ　ニ　木　あ　く　ん　笑
ユーザー Taiki0715
提出日時 2025-07-18 21:43:10
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 159 ms / 3,000 ms
コード長 10,418 bytes
コンパイル時間 3,807 ms
コンパイル使用メモリ 294,036 KB
実行使用メモリ 89,172 KB
最終ジャッジ日時 2025-07-18 21:43:24
合計ジャッジ時間 7,031 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge2
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 * 30
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 # 

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>istream &operator>>(istream &is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}
template<typename T1,typename T2,typename T3>istream &operator>>(istream &is,tuple<T1,T2,T3>&a){is>>std::get<0>(a)>>std::get<1>(a)>>std::get<2>(a);return is;}
template<typename T,size_t n>istream &operator>>(istream &is,array<T,n>&a){for(auto&i:a)is>>i;return is;}
template<typename T>istream &operator>>(istream &is,vector<T> &a){for(auto &i:a)is>>i;return is;}
template<typename T1,typename T2>void operator++(pair<T1,T2>&a,int n){a.first++,a.second++;}
template<typename T1,typename T2>void operator--(pair<T1,T2>&a,int n){a.first--,a.second--;}
template<typename T>void operator++(vector<T>&a,int n){for(auto &i:a)i++;}
template<typename T>void operator--(vector<T>&a,int n){for(auto &i:a)i--;}
#define overload3(_1,_2,_3,name,...) name
#define rep1(i,n) for(int i=0;i<(int)(n);i++)
#define rep2(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define rep(...) overload3(__VA_ARGS__,rep2,rep1)(__VA_ARGS__)
#define reps(i,l,r) rep2(i,l,r)
#define all(x) x.begin(),x.end()
#define pcnt(x) __builtin_popcountll(x)
#define fin(x) return cout<<(x)<<'\n',static_cast<void>(0)
#define yn(x) cout<<((x)?"Yes\n":"No\n")
#define uniq(x) sort(all(x)),x.erase(unique(all(x)),x.end())
template<typename T>
inline int fkey(vector<T>&z,T key){return lower_bound(z.begin(),z.end(),key)-z.begin();}
ll myceil(ll a,ll b){return (a+b-1)/b;}
template<typename T,size_t n,size_t id=0>
auto vec(const int (&d)[n],const T &init=T()){
  if constexpr (id<n)return vector(d[id],vec<T,n,id+1>(d,init));
  else return init;
}
#ifdef LOCAL
#include<debug.h>
#define SWITCH(a,b) (a)
#else
#define debug(...) static_cast<void>(0)
#define debugg(...) static_cast<void>(0)
#define SWITCH(a,b) (b)
template<typename T1,typename T2>ostream &operator<<(ostream &os,const pair<T1,T2>&p){os<<p.first<<' '<<p.second;return os;}
#endif
struct Timer{
  clock_t start;
  Timer(){
    start=clock();
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout<<fixed<<setprecision(16);
  }
  inline double now(){return (double)(clock()-start)/1000;}
  #ifdef LOCAL
  ~Timer(){
    cerr<<"time:";
    cerr<<now();
    cerr<<"ms\n";
  }
  #endif
}timer;
void SOLVE();
int main(){
  int testcase=1;
  //cin>>testcase;
  for(int i=0;i<testcase;i++){
    SOLVE();
  }
}
template<typename T=int>
struct Edge{
  int from,to;
  T weight;
  int index;
  Edge(int from_,int to_,T weight_=T(),int index_=-1):from(from_),to(to_),weight(weight_),index(index_){}
  Edge():from(-1),to(-1),weight(),index(-1){}
  friend std::ostream &operator<<(std::ostream &os,const Edge&e){
    os<<'[';
    os<<"from:"<<e.from;
    os<<"to:"<<e.to;
    os<<"weight:"<<e.weight;
    os<<"index:"<<e.index;
    os<<']';
    return os;
  }
};
template<typename T=int>
struct Tree{
protected:
  int n,r;
  std::vector<Edge<T>>edge;
  std::vector<Edge<T>>g;
  std::vector<int>ptr;
  struct tree_range{
    using iterator=typename std::vector<Edge<T>>::iterator;
    iterator l,r;
    iterator begin()const{return l;}
    iterator end()const{return r;}
    int size()const{return r-l;}
    bool empty()const{return !size();}
    Edge<T> &operator[](int i)const{return l[i];}
  };
  struct const_tree_range{
    using iterator=typename std::vector<Edge<T>>::const_iterator;
    iterator l,r;
    iterator begin()const{return l;}
    iterator end()const{return r;}
    int size()const{return r-l;}
    bool empty()const{return !size();}
    const Edge<T> &operator[](int i)const{return l[i];}
  };
public:
  explicit Tree(int n_):n(n_){
    edge.reserve(n-1);
  }
  Tree():n(0){}
  Tree(int n_,const std::vector<Edge<T>>&e,bool dir=false):n(n_),r(-1),edge(e){
    if(!dir)build();
    else{
      std::vector<bool>seen(n,false);
      ptr.resize(n+1);
      for(const Edge<T>&i:edge)ptr[i.from]++,ptr[i.to]++,seen[e.to]=true;
      for(int i=1;i<=n;i++)ptr[i]+=ptr[i-1];
      r=std::find(seen.begin(),seen.end(),false)-seen.begin();
      assert(ptr[n]==n*2-2);
      g.resize(ptr[n]);
      for(const Edge<T>&i:edge)g[--ptr[i.to]]=Edge<T>(i.to,i.from,i.weight,i.index);
      for(const Edge<T>&i:edge)g[--ptr[i.from]]=i;
    }
  }
  template<bool weighted=false,bool index=1>
  void read(){
    for(int i=0;i<n-1;i++){
      int u,v;
      T w=T();
      std::cin>>u>>v;
      if constexpr(index)u--,v--;
      if constexpr(weighted)std::cin>>w;
      else w=1;
      edge.emplace_back(u,v,w,i);
    }
    build();
  }
  template<bool index=1>
  void readp(){
    ptr.resize(n+1);
    for(int i=1;i<n;i++){
      int p;
      std::cin>>p;
      if constexpr(index)p--;
      edge.emplace_back(p,i,1,i-1);
      ptr[p]++;
      ptr[i]++;
    }
    for(int i=1;i<=n;i++)ptr[i]+=ptr[i-1];
    g.resize(n*2-2);
    for(auto&&[u,v,w,i]:edge)g[--ptr[v]]=Edge<T>(v,u,w,i);
    for(int i=0;i<n-1;i++){
      g[--ptr[edge[i].from]]=edge[i];
    }
  }
  void add_edge(int u,int v){edge.emplace_back(u,v,1,edge.size());}
  void add_edge(int u,int v,T w){edge.emplace_back(u,v,w,edge.size());}
  void add_edge(int u,int v,T w,int idx){edge.emplace_back(u,v,w,idx);}
  inline bool is_directed()const{return r!=-1;}
  void build(){
    r=-1;
    ptr.resize(n+1,0);
    for(auto&&[u,v,w,i]:edge)ptr[u]++,ptr[v]++;
    for(int i=1;i<=n;i++)ptr[i]+=ptr[i-1];
    assert(ptr[n]==n*2-2);
    g.resize(n*2-2);
    for(auto&&[u,v,w,i]:edge){
      g[--ptr[u]]=Edge(u,v,w,i);
      g[--ptr[v]]=Edge(v,u,w,i);
    }
  }
  void remove_parent(int root=0){
    edge.resize(n-1);
    std::vector<int>par(n,-1);
    par[root]=-1;
    std::queue<int>que;
    que.push(root);
    while(!que.empty()){
      int x=que.front();
      que.pop();
      for(int i=ptr[x];i<ptr[x+1];){
        const Edge<T>&e=g[i];
        if(e.to!=par[x]){
          par[e.to]=x;
          edge[e.index]=e;
          que.push(e.to);
          i++;
        }
        else{
          if(i+1==ptr[x+1])break;
          std::swap(g[i],g[ptr[x+1]-1]);
        }
      }
    }
    r=root;
  }
  std::vector<int>bfs_order()const{
    assert(is_directed());
    std::vector<int>bfs(n);
    int p=0,q=0;
    bfs[q++]=root();
    while(p<q){
      int x=bfs[p++];
      for(const Edge<T>&e:(*this)[x])bfs[q++]=e.to;
    }
    return bfs;
  }
  std::vector<int>dfs_order()const{
    assert(is_directed());
    std::vector<int>res;
    res.reserve(n);
    std::vector<int>st(n);
    int p=0;
    st[p++]=root();
    while(p){
      int x=st[--p];
      res.push_back(x);
      p+=(*this)[x].size();
      for(const Edge<T>&e:(*this)[x])st[--p]=e.to;
      p+=(*this)[x].size();
    }
    return res;
  }
  std::vector<int>rbfs_order()const{
    std::vector<int>bfs=bfs_order();
    std::reverse(bfs.begin(),bfs.end());
    return bfs;
  }
  void hld(){
    assert(is_directed());
    std::vector<int>sub(n);
    for(int x:rbfs_order()){
      sub[x]=1;
      int mx=-1;
      for(Edge<T>&e:(*this)[x]){
        sub[x]+=sub[e.to];
        if(mx<sub[e.to]){
          mx=sub[e.to];
          std::swap((*this)[x][0],e);
        }
      }
    }
  }
  std::pair<std::vector<int>,std::vector<int>>in_out_order(){
    assert(is_directed());
    std::vector<int>in(n),out(n);
    int p=0;
    auto dfs=[&](auto self,int x)->void {
      in[x]=p++;
      for(const Edge<T>&e:(*this)[x]){
        self(self,e.to);
      }
      out[x]=p;
    };
    dfs(dfs,root());
    return std::make_pair(in,out);
  }
  std::pair<T,std::vector<int>>diameter()const{
    assert(!is_directed());
    static constexpr T inf=std::numeric_limits<T>::max();
    std::vector<T>dst(n,inf);
    dst[0]=0;
    std::vector<int>que(n);
    int p=0,q=1;
    que[0]=0;
    while(p<q){
      int x=que[p++];
      for(const Edge<T>&e:(*this)[x])if(dst[e.to]==inf){
        dst[e.to]=dst[x]+e.weight;
        que[q++]=e.to;
      }
    }
    int u=std::max_element(dst.begin(),dst.end())-dst.begin();
    std::fill(dst.begin(),dst.end(),inf);
    dst[u]=0;
    p=0,q=1;
    que[0]=u;
    while(p<q){
      int x=que[p++];
      for(const Edge<T>&e:(*this)[x])if(dst[e.to]==inf){
        dst[e.to]=dst[x]+e.weight;
        que[q++]=e.to;
      }
    }
    int v=std::max_element(dst.begin(),dst.end())-dst.begin();
    T weight=dst[v];
    std::vector<int>res;
    while(u!=v){
      res.push_back(v);
      for(const Edge<T>&e:(*this)[v])if(dst[e.to]<dst[v]){
        v=e.to;
        break;
      }
    }
    res.push_back(u);
    return std::make_pair(weight,res);
  }
  int size()const{return n;}
  tree_range operator[](int i){return tree_range{g.begin()+ptr[i],g.begin()+ptr[i+1]-(r!=-1&&r!=i)};}
  const_tree_range operator[](int i)const{return const_tree_range{g.begin()+ptr[i],g.begin()+ptr[i+1]-(r!=-1&&r!=i)};}
  const Edge<T>& get_edge(int i)const{return edge[i];}
  inline int parent(int i)const{return i==r?-1:g[ptr[i+1]-1].to;}
  inline int root()const{return r;}
  typename std::vector<Edge<T>>::iterator begin(){return edge.begin();}
  typename std::vector<Edge<T>>::iterator end(){return edge.end();}
  typename std::vector<Edge<T>>::const_iterator begin()const{return edge.begin();}
  typename std::vector<Edge<T>>::const_iterator end()const{return edge.end();}
};
void SOLVE(){
  int n;
  cin>>n;
  Tree t(n);
  t.read();
  vector<int>dep(n);
  int ans=0;
  auto dfs=[&](auto self,int x,int p)->void {
    dep[x]=1;
    for(auto e:t[x])if(e.to!=p){
      self(self,e.to,x);
      chmax(dep[x],dep[e.to]+1);
    }
  };
  auto dfs2=[&](auto self,int x,int p)->void {
    vector<int>adj;
    for(auto e:t[x])adj.push_back(dep[e.to]);
    sort(all(adj));
    rep(i,adj.size()){
      chmax<int>(ans,1+adj[i]*(adj.size()-i));
    }
    vector<int>left(t[x].size()),right(t[x].size());
    rep(i,t[x].size())left[i]=right[i]=dep[t[x][i].to];
    rep(i,1,left.size())chmax(left[i],left[i-1]);
    for(int i=ssize(right)-2;i>=0;i--)chmax(right[i],right[i+1]);
    rep(i,t[x].size())if(t[x][i].to!=p){
      dep[x]=0;
      if(i)chmax(dep[x],left[i-1]);
      if(i+1!=t[x].size())chmax(dep[x],right[i+1]);
      dep[x]++;
      self(self,t[x][i].to,x);
    }
  };
  dfs(dfs,0,-1);
  dfs2(dfs2,0,-1);
  cout<<ans<<endl;
}
0