#516256 (C++17) No.1124 Earthquake Safety

• 問題: No.1124 Earthquake Safety
• ユーザー: beet
• 提出日時: 2020-07-22 22:05:35
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: TLE
• 実行時間: -
• コード長: 7,146 bytes
• コンパイル時間: 3,195 ms
• コンパイル使用メモリ: 224,792 KB
• 最終ジャッジ日時: 2025-01-12 02:48:48
• ジャッジサーバーID （参考情報）: judge3 / judge5

ファイルパターン	結果
other	AC * 56 TLE * 2

ソースコード

#include <bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
using Int = long long;
const char newl = '\n';


template<typename T,T MOD = 1000000007>
struct Mint{
  static constexpr T mod = MOD;
  T v;
  Mint():v(0){}
  Mint(signed v):v(v){}
  Mint(long long t){v=t%MOD;if(v<0) v+=MOD;}

  Mint pow(long long k){
    Mint res(1),tmp(v);
    while(k){
      if(k&1) res*=tmp;
      tmp*=tmp;
      k>>=1;
    }
    return res;
  }

  static Mint add_identity(){return Mint(0);}
  static Mint mul_identity(){return Mint(1);}

  Mint inv(){return pow(MOD-2);}

  Mint& operator+=(Mint a){v+=a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator-=(Mint a){v+=MOD-a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator*=(Mint a){v=1LL*v*a.v%MOD;return *this;}
  Mint& operator/=(Mint a){return (*this)*=a.inv();}

  Mint operator+(Mint a) const{return Mint(v)+=a;}
  Mint operator-(Mint a) const{return Mint(v)-=a;}
  Mint operator*(Mint a) const{return Mint(v)*=a;}
  Mint operator/(Mint a) const{return Mint(v)/=a;}

  Mint operator-() const{return v?Mint(MOD-v):Mint(v);}

  bool operator==(const Mint a)const{return v==a.v;}
  bool operator!=(const Mint a)const{return v!=a.v;}
  bool operator <(const Mint a)const{return v <a.v;}

  static Mint comb(long long n,int k){
    Mint num(1),dom(1);
    for(int i=0;i<k;i++){
      num*=Mint(n-i);
      dom*=Mint(i+1);
    }
    return num/dom;
  }
};
template<typename T,T MOD> constexpr T Mint<T, MOD>::mod;
template<typename T,T MOD>
ostream& operator<<(ostream &os,Mint<T, MOD> m){os<<m.v;return os;}


template<typename F>
struct FixPoint : F{
  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)};
}




struct Centroid{
  vector<int> sz,dead;
  vector< vector<int> > G;
  Centroid(){}
  Centroid(int n):sz(n,1),dead(n,0),G(n){}

  void add_edge(int u,int v){
    G[u].emplace_back(v);
    G[v].emplace_back(u);
  }

  int dfs(int v,int p){
    sz[v]=1;
    for(int u:G[v])
      if(u!=p&&!dead[u]) sz[v]+=dfs(u,v);
    return sz[v];
  }

  void find(int v,int p,int tmp,vector<int> &cs) {
    int ok=1;
    for (int u:G[v]){
      if(u==p||dead[u]) continue;
      find(u,v,tmp,cs);
      ok&=(sz[u]<=tmp/2);
    }
    ok&=(tmp-sz[v]<=tmp/2);
    if(ok) cs.emplace_back(v);
  }

  vector<int> build(int r) {
    int tmp=dfs(r,-1);
    vector<int> cs;
    find(r,-1,tmp,cs);
    return cs;
  }

  const vector<int>& operator[](int k)const{return G[k];}
  void disable(int v){dead[v]=1;}
  void  enable(int v){dead[v]=0;}
  int alive(int v){return !dead[v];}
};


namespace FFT{
  using dbl = double;

  struct num{
    dbl x,y;
    num(){x=y=0;}
    num(dbl x,dbl y):x(x),y(y){}
  };

  inline num operator+(num a,num b){
    return num(a.x+b.x,a.y+b.y);
  }
  inline num operator-(num a,num b){
    return num(a.x-b.x,a.y-b.y);
  }
  inline num operator*(num a,num b){
    return num(a.x*b.x-a.y*b.y,a.x*b.y+a.y*b.x);
  }
  inline num conj(num a){
    return num(a.x,-a.y);
  }

  int base=1;
  vector<num> rts={{0,0},{1,0}};
  vector<int> rev={0,1};

  const dbl PI=asinl(1)*2;

  void ensure_base(int nbase){
    if(nbase<=base) return;

    rev.resize(1<<nbase);
    for(int i=0;i<(1<<nbase);i++)
      rev[i]=(rev[i>>1]>>1)+((i&1)<<(nbase-1));

    rts.resize(1<<nbase);
    while(base<nbase){
      dbl angle=2*PI/(1<<(base+1));
      for(int i=1<<(base-1);i<(1<<base);i++){
        rts[i<<1]=rts[i];
        dbl angle_i=angle*(2*i+1-(1<<base));
        rts[(i<<1)+1]=num(cos(angle_i),sin(angle_i));
      }
      base++;
    }
  }

  void fft(vector<num> &as){
    int n=as.size();
    assert((n&(n-1))==0);

    int zeros=__builtin_ctz(n);
    ensure_base(zeros);
    int shift=base-zeros;
    for(int i=0;i<n;i++)
      if(i<(rev[i]>>shift))
        swap(as[i],as[rev[i]>>shift]);

    for(int k=1;k<n;k<<=1){
      for(int i=0;i<n;i+=2*k){
        for(int j=0;j<k;j++){
          num z=as[i+j+k]*rts[j+k];
          as[i+j+k]=as[i+j]-z;
          as[i+j]=as[i+j]+z;
        }
      }
    }
  }

  template<typename T>
  vector<long long> multiply(vector<T> &as,vector<T> &bs){
    int need=as.size()+bs.size()-1;
    int nbase=0;
    while((1<<nbase)<need) nbase++;
    ensure_base(nbase);

    int sz=1<<nbase;
    vector<num> fa(sz);
    for(int i=0;i<sz;i++){
      T x=(i<(int)as.size()?as[i]:0);
      T y=(i<(int)bs.size()?bs[i]:0);
      fa[i]=num(x,y);
    }
    fft(fa);

    num r(0,-0.25/sz);
    for(int i=0;i<=(sz>>1);i++){
      int j=(sz-i)&(sz-1);
      num z=(fa[j]*fa[j]-conj(fa[i]*fa[i]))*r;
      if(i!=j)
        fa[j]=(fa[i]*fa[i]-conj(fa[j]*fa[j]))*r;
      fa[i]=z;
    }
    fft(fa);

    vector<long long> res(need);
    for(int i=0;i<need;i++)
      res[i]=round(fa[i].x);

    return res;
  }

};

//INSERT ABOVE HERE

using M = Mint<int>;
M calc(vector<vector<int>> H){
  int n=H.size();
  Centroid G(n);
  G.G=H;

  queue<int> que;
  que.emplace(G.build(0)[0]);

  using ll = long long;
  vector<ll> ans(n,0);
  while(!que.empty()){
    int r=que.front();que.pop();

    vector<ll> cnt;
    cnt.emplace_back(1);
    for(int c:G[r]){
      if(!G.alive(c)) continue;
      vector<ll> num;
      MFP([&](auto dfs,int v,int p,int d)->void{
        while((int)cnt.size()<=d)
          cnt.emplace_back(0);
        while((int)num.size()<=d)
          num.emplace_back(0);
        cnt[d]++;
        num[d]++;
        for(int u:G[v]){
          if(u==p or !G.alive(u)) continue;
          dfs(u,v,d+1);
        }
      })(c,r,1);
      auto ns=FFT::multiply(num,num);
      for(int i=0;i<min(n,(int)ns.size());i++) ans[i]-=ns[i];
    }
    auto cs=FFT::multiply(cnt,cnt);
    for(int i=0;i<min(n,(int)cs.size());i++) ans[i]+=cs[i];

    G.disable(r);
    for(int c:G[r])
      if(G.alive(c))
        que.emplace(G.build(c)[0]);
  }
  M res{0};
  // 1 point
  res+=M(n)*M(2).pow(n-1);

  // 2 points (distinct)
  for(int d=1;d<n;d++)
    res+=M(ans[d])*M(2).pow(n-(d+1))*M(3);
  return res;
}

signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  int n;
  cin>>n;
  vector<vector<int>> G(n);
  for(int i=1;i<n;i++){
    int a,b;
    cin>>a>>b;
    a--;b--;
    G[a].emplace_back(b);
    G[b].emplace_back(a);
  }
  M ans{0};

  vector<M> dp1(n),dp2(n);
  // 3 points (distinct)
  MFP([&](auto dfs,int v,int p)->void{
    vector<M> cur(4,0);
    cur[0]=M(1);
    cur[1]=M(1);

    for(int u:G[v]){
      if(u==p) continue;
      dfs(u,v);
      vector<M> nxt(4,0);

      nxt[0]+=cur[0];
      nxt[1]+=cur[0]*dp1[u];
      nxt[2]+=cur[0]*dp2[u]/M(2);

      nxt[1]+=cur[1];
      nxt[2]+=cur[1]*dp1[u];
      nxt[3]+=cur[1]*dp2[u]/M(2);

      nxt[2]+=cur[2];
      nxt[3]+=cur[2]*dp1[u];

      nxt[3]+=cur[3];
      swap(cur,nxt);
    }

    dp1[v]=cur[1]*M(1)/M(2);
    dp2[v]=cur[2]*M(2)/M(2);
    ans+=cur[3]*M(6);
  })(0,-1);
  ans*=M(2).pow(n-1);

  ans+=calc(G);
  cout<<ans<<newl;
  return 0;
}