test/aoj/2222.test.cpp

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Last update: 2021-03-25 09:46:10+09:00
Problem: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2222

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Code

// verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2222

#include<bits/stdc++.h>
using namespace std;

#define call_from_test
#include "../../mod/mint.cpp"
#include "../../graph/stronglyconnectedcomponent.cpp"
#undef call_from_test

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

  using M = Mint<int>;

  int n,m;
  cin>>n>>m;

  SCC scc(n);
  for(int i=0;i<m;i++){
    int s,d;
    cin>>s>>d;
    s--;d--;
    scc.add_edge(s,d);
  }

  int k=scc.build();
  vector<M> dp(k,1);
  vector<int> indeg(k,0);

  M ans(1);
  for(int i=0;i<k;i++){
    if(indeg[i]!=0) dp[i]-=M(1);
    for(int j:scc.H[i])
      dp[j]*=dp[i]+M(1);
    if(scc.H[i].empty()) ans*=dp[i]+M(1);
  }

  cout<<ans<<endl;
  return 0;
}

#line 1 "test/aoj/2222.test.cpp"
// verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2222

#include<bits/stdc++.h>
using namespace std;

#define call_from_test
#line 1 "mod/mint.cpp"

#line 3 "mod/mint.cpp"
using namespace std;
#endif

//BEGIN CUT HERE
template<typename T, T MOD = 1000000007>
struct Mint{
  inline 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 *this;}
  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;}

  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>
ostream& operator<<(ostream &os,Mint<T, MOD> m){os<<m.v;return os;}
//END CUT HERE
#ifndef call_from_test
signed main(){
  return 0;
}
#endif
#line 1 "graph/stronglyconnectedcomponent.cpp"

#line 3 "graph/stronglyconnectedcomponent.cpp"
using namespace std;
#endif
//BEGIN CUT HERE
struct SCC{
  vector< vector<int> > G,R,H,C;
  vector<int> vs,used,blg;
  SCC(int n):G(n),R(n),used(n),blg(n){}

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

  void dfs(int v){
    used[v]=1;
    for(int u:G[v])
      if(!used[u]) dfs(u);
    vs.emplace_back(v);
  }

  void rdfs(int v,int k){
    used[v]=1;
    blg[v]=k;
    C[k].emplace_back(v);
    for(int u:R[v])
      if(!used[u]) rdfs(u,k);
  }

  int build(bool uniq=true){
    int n=G.size();
    for(int v=0;v<n;v++)
      if(!used[v]) dfs(v);

    fill(used.begin(),used.end(),0);
    int k=0;
    for(int i=n-1;i>=0;i--){
      if(!used[vs[i]]){
        H.emplace_back();
        C.emplace_back();
        rdfs(vs[i],k++);
      }
    }

    for(int v=0;v<n;v++)
      for(int u:G[v])
        if(blg[v]!=blg[u])
          H[blg[v]].emplace_back(blg[u]);

    if(uniq){
      for(int i=0;i<k;i++){
        sort(H[i].begin(),H[i].end());
        H[i].erase(unique(H[i].begin(),H[i].end()),H[i].end());
      }
    }
    return k;
  }

  int operator[](int k) const{return blg[k];}
};
//END CUT HERE
#ifndef call_from_test
signed main(){
  return 0;
}
#endif
#line 9 "test/aoj/2222.test.cpp"
#undef call_from_test

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

  using M = Mint<int>;

  int n,m;
  cin>>n>>m;

  SCC scc(n);
  for(int i=0;i<m;i++){
    int s,d;
    cin>>s>>d;
    s--;d--;
    scc.add_edge(s,d);
  }

  int k=scc.build();
  vector<M> dp(k,1);
  vector<int> indeg(k,0);

  M ans(1);
  for(int i=0;i<k;i++){
    if(indeg[i]!=0) dp[i]-=M(1);
    for(int j:scc.H[i])
      dp[j]*=dp[i]+M(1);
    if(scc.H[i].empty()) ans*=dp[i]+M(1);
  }

  cout<<ans<<endl;
  return 0;
}