Submission #542512

#	Time	Username	Problem	Language	Result	Execution time	Memory
542512		inksamurai	Šarenlist (COCI22_sarenlist)	C++17	10 / 110	1 ms	212 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define rng(i,x,n) for(int i=x;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define vec(...) vector<__VA_ARGS__>
#define _3wByxeT ios::sync_with_stdio(0),cin.tie(0)
typedef long long ll;
using pii=pair<int,int>;
using vi=vector<int>;
void print(){cout<<'\n';}
template<class h,class...t>
void print(const h&v,const t&...u){cout<<v<<' ',print(u...);}
// e

//snuke's mod int
template <ll mod>
struct modint{
	ll x; // typedef long long ll;
	modint(ll x=0):x((x%mod+mod)%mod){}
	modint operator-()const{return modint(-x);}
	modint& operator+=(const modint a){if((x+=a.x)>=mod) x-=mod; return *this;}
	modint& operator-=(const modint a){if((x+=mod-a.x)>=mod) x-=mod; return *this;}
	modint& operator*=(const modint a){(x*=a.x)%=mod; return *this;}
	modint operator+(const modint a)const{modint res(*this); return res+=a;}
	modint operator-(const modint a)const{modint res(*this); return res-=a;}
	modint operator*(const modint a)const{modint res(*this); return res*=a;}
	modint pow(ll n)const{
		modint res=1,x(*this);
		while(n){
			if(n&1)res*=x;
			x*=x;
			n>>=1;
		}
		return res;
	}
	modint inv()const{return pow(mod-2);}
};
using mint=modint<1000'000'007>;

signed main(){
_3wByxeT;
	int n,m,k;
	cin>>n>>m>>k;

	vec(vi) adj(n);
	rep(i,n-1){
		int u,v;
		cin>>u>>v;
		u-=1,v-=1;
		adj[u].pb(v);
		adj[v].pb(u);
	}

	using vp=vec(pii);
	vp es;
	rep(i,m){
		int u,v;
		cin>>u>>v;
		u-=1,v-=1;
		es.pb({u,v});
	}

	mint ans=0;

	rng(msk,1,(1<<m)){
		std::map<pii,int> mp;

		auto dfs=[&](auto self,int v,int par,int nd)->bool{
			if(v==nd) return 1;
			bool sok=0;
			for(auto u:adj[v]){
				if(u==par) continue;
				bool pok=self(self,u,v,nd);
				if(pok){
					mp[minmax(u,v)]=1;
				}
				sok=sok or pok;
			}
			return sok;
		};

		auto add=[&](int u,int v){
			dfs(dfs,v,-1,u);
		};

		rep(i,m){
			if(msk>>i&1){
				auto [u,v]=es[i];
				add(u,v);
			}
		}

		int now=sz(mp);
		assert(now);
		if(__builtin_popcount(msk)%2){
			ans-=mint(k)*mint(k).pow(n-1-now);
		}else{
			ans+=mint(k)*mint(k).pow(n-1-now);
		}
	}

	ans+=mint(k).pow(n-1);
	print(ans.x);
//
	return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 65