Submission #639413

#	Time	Username	Problem	Language	Result	Execution time	Memory
639413		inksamurai	Usmjeri (COCI17_usmjeri)	C++17	140 / 140	603 ms	146896 KiB

usmjeri

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define rng(i,c,n) for(int i=c;i<n;i++)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define vec(...) vector<__VA_ARGS__>
#define _3xaMC2q 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

#define vp vec(pii)

const int _n=300001,lon=21;

int n,m;
vi adj[_n];
map<pii,int> es;

int spr[lon][_n*3+11],prs[lon][_n];
int par[_n],dpth[_n],tin[_n];
int _tm;
vi tour;

void dfs(int v){
	tin[v]=_tm++;
	tour.pb(v);
	for(auto u:adj[v]){
		if(u==par[v]) continue;
		dpth[u]=dpth[v]+1;
		par[u]=v;
		dfs(u);
		tour.pb(v);
		_tm++;
	}
}

int chmin(int v,int u){
	return dpth[v]<dpth[u]?v:u;
}

void _gap_lca(){
	dfs(0);
	rep(i,n){
		prs[0][i]=par[i];
	}
	rng(j,1,lon){
		rep(i,n){
			int up=prs[j-1][i];
			prs[j][i]=up==-1?up:prs[j-1][up];
		}
	}
	const int si_to=sz(tour);
	rep(i,si_to){
		spr[0][i]=tour[i];
		if(i+1<si_to){
			spr[0][i]=chmin(spr[0][i],tour[i+1]);
		}
	}
	rng(j,1,lon){
		rep(i,si_to){
			int up=spr[j-1][i];
			if(i+(1<<(j-1))<si_to){
				up=chmin(up,spr[j-1][i+(1<<(j-1))]);
			}
			spr[j][i]=up;
		}
	}
}

int get_ancestor(int u,int v){
	int i=tin[u],j=tin[v];
	if(i==j) return v;
	if(i>j)swap(i,j),swap(u,v);
	int k=31-__builtin_clz(j-i);
	u=spr[k][i];
	v=spr[k][j-(1<<k)];
	return chmin(u,v);
}

int get_dist(int u,int v){
	int up=get_ancestor(u,v);
	return dpth[v]+dpth[u]-2*dpth[up];
}

int push_up(int s,int d){
	per(i,lon){
		if(d>>i&1){
			s=prs[i][s];
		}
	}
	return s;
}

signed main(){
_3xaMC2q;
	cin>>n>>m;
	rep(i,n-1){
		int u,v;
		cin>>u>>v;
		u-=1,v-=1;
		es[minmax(u,v)]=i;
		adj[u].pb(v);
		adj[v].pb(u);
	}
	_gap_lca();
	vi rbe(n,-1);
	//denotes edge from (i,pari)
	vec(vp) g(n-1);
	//denotes graph of edges in inital graph
	rep(i,m){
		int s,t;
		cin>>s>>t;
		s-=1,t-=1;
		if(dpth[s]>dpth[t])swap(s,t);
		if(s!=t){
			int up=get_ancestor(s,t);
			if(up!=s){
				int ds=get_dist(s,up);
				int ns=push_up(s,ds-1);
				int id=s;
				rbe[id]=rbe[id]==-1?ns:chmin(rbe[id],ns);
				int dt=get_dist(t,up);
				int nt=push_up(t,dt-1);
				id=t;
				rbe[id]=rbe[id]==-1?nt:chmin(rbe[id],nt);
				int u=es[minmax(ns,up)],v=es[minmax(nt,up)];
				g[u].pb(pii(1,v));
				g[v].pb(pii(1,u));
			}else{
				int dt=get_dist(t,up);
				int nt=push_up(t,dt-1);
				int id=t;
				rbe[id]=rbe[id]==-1?nt:chmin(rbe[id],nt);
			}
		}
	}
	//add additional edges from rbe
	vi rbts;
	rep(i,n)rbts.pb(i);
	sort(rbts.begin(),rbts.end(),[&](int l,int r){return dpth[l]>dpth[r];});
	for(auto s:rbts){
		if(rbe[s]!=-1){
			if(dpth[rbe[s]]<dpth[s]){
				int up=rbe[s];
				rbe[par[s]]=rbe[par[s]]==-1?up:chmin(rbe[par[s]],up);
				int u=es[minmax(s,par[s])],v=es[minmax(par[s],par[par[s]])];
				g[u].pb(pii(0,v));
				g[v].pb(pii(0,u));
			}
		}
	}
	bool valid=1;
	vi usd(n-1,-1);
	auto rfs=[&](auto self,int v)->void{
		for(auto e:g[v]){
			int u=e.se;
			int w=e.fi;
			if(usd[u]==-1){
				usd[u]=usd[v]^w;
				self(self,u);
			}else if(usd[u]!=(usd[v]^w)){
				valid=0;
			}
		}
	};
	ll ans=1;
	const ll mod=1000000007;
	rep(i,n-1){
		if(usd[i]==-1){
			usd[i]=0;
			ans=ans*2%mod;
			ans%=mod;
			rfs(rfs,i);
		}
	}
	if(!valid){
		print(0);
	}else{
		print(ans);
	}
}

• Subtask 1: 14 / 14
• Subtask 2: 14 / 14
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 14 / 14
• Subtask 6: 14 / 14
• Subtask 7: 14 / 14
• Subtask 8: 14 / 14
• Subtask 9: 14 / 14
• Subtask 10: 14 / 14