This documentation is automatically generated by online-judge-tools/verification-helper
View the Project on GitHub beet-aizu/library
// verification-helper: PROBLEM https://yukicoder.me/problems/1665 #include<bits/stdc++.h> using namespace std; #define call_from_test #include "../../math/totient_table.cpp" #include "../../mod/mint.cpp" #undef call_from_test signed main(){ cin.tie(0); ios::sync_with_stdio(0); int n,m; cin>>n>>m; auto ts=totient_table(n/m+1); using M = Mint<int>; M ans{0}; for(int i=2;i<=n/m;i++) ans+=M(ts[i]*2); for(int i=1;i<=n-2;i++) ans*=M(i); cout<<ans<<endl; return 0; }
#line 1 "test/yukicoder/1665.test.cpp" // verification-helper: PROBLEM https://yukicoder.me/problems/1665 #include<bits/stdc++.h> using namespace std; #define call_from_test #line 1 "math/totient_table.cpp" #line 3 "math/totient_table.cpp" using namespace std; #endif //BEGIN CUT HERE vector<int> totient_table(int n){ vector<int> ts(n+1); iota(ts.begin(),ts.end(),0); for(int i=2;i<=n;i++){ if(ts[i]!=i) continue; for(int j=i;j<=n;j+=i) ts[j]=ts[j]/i*(i-1); } return ts; } //END CUT HERE #ifndef call_from_test //INSERT ABOVE HERE signed main(){ return 0; } #endif #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 9 "test/yukicoder/1665.test.cpp" #undef call_from_test signed main(){ cin.tie(0); ios::sync_with_stdio(0); int n,m; cin>>n>>m; auto ts=totient_table(n/m+1); using M = Mint<int>; M ans{0}; for(int i=2;i<=n/m;i++) ans+=M(ts[i]*2); for(int i=1;i<=n-2;i++) ans*=M(i); cout<<ans<<endl; return 0; }