Submission #654920

#	Time	Username	Problem	Language	Result	Execution time	Memory
654920		inksamurai	Village (BOI20_village)	C++17	12 / 100	2 ms	724 KiB

Village

#include <bits/stdc++.h>
#define int ll
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 _3fm6nhZ 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...);}

#define all(a) a.begin(),a.end()

signed main(){
_3fm6nhZ;
	int n;
	cin>>n;
	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);
	}
	int ans=0;
	vi ert(n);
	auto dfs=[&](auto self,int v,int par)->int{
		vi rbts;
		for(auto u:adj[v]){
			if(u==par) continue;
			int e=self(self,u,v);
			if(e) rbts.pb(u);
		}
		if(sz(rbts)==0) return 1;
		for(int i=0;i<sz(rbts)-sz(rbts)%2;i+=2){
			ert[rbts[i]]=rbts[i+1];
			ert[rbts[i+1]]=rbts[i];
			ans+=4;
		}
		if(sz(rbts)%2){
			ert[v]=rbts.back();
			ert[rbts.back()]=v;
			ans+=2;
		}else{
			ert[v]=rbts.back();
			ert[ert[rbts.back()]]=v;
		}
		return 0;
	};
	int e=dfs(dfs,0,-1);
	if(e){
		int v=0;
		int u=adj[0][0];
		ans+=2;
		rep(s,n){
			if(ert[s]==u){
				ert[v]=u;
				ert[s]=0;
				break;
			}
		}
	}
	int ans1=0;
	vi chs(n);
	auto pre_rfs=[&](auto self,int v,int par)->void{
		chs[v]=1;
		for(auto u:adj[v]){
			if(u==par) continue;
			self(self,u,v);
			chs[v]+=chs[u];
			ans1+=2*min(chs[u],n-chs[u]);
		}
	};
	pre_rfs(pre_rfs,0,-1);
	auto rfs=[&](auto self,int v,int par)->int{
		for(auto u:adj[v]){
			if(u==par) continue;
			if(2*chs[u]>=n){
				return self(self,u,v);
			}
		}
		return v;
	};
	int rt=rfs(rfs,0,-1);
	chs=vi(n,0);
	ans1=0;
	pre_rfs(pre_rfs,rt,-1);
	vi way;
	auto add=[&](auto self,int v,int par)->void{
		way.pb(v);
		for(auto u:adj[v]){
			if(u==par) continue;
			self(self,u,v);
		}
	};
	sort(all(adj[rt]),[&](int l,int r){
		return chs[l]<chs[r];
	});
	vec(vi) rbts;
	for(auto u:adj[rt]){
		way.clear();
		add(add,u,rt);
		rbts.pb(way);
	}
	set<int> st;
	rep(i,n){
		st.insert(i);
	}
	vi usd(n);
	vi ert1(n);
	auto ask=[&](auto self,int v,int par)->void{
		if(!sz(st)){
			cout<<"asdasdasdhi\n";
		}
		assert(sz(st));
		if(st.find(rt)!=st.end()){
			usd[rt]=1;
			ert1[rt]=v;
			st.erase(st.find(rt));
		}else{
			auto it=st.begin();
			usd[*it]=1;
			ert1[*it]=v;
			st.erase(it);
		}
		for(auto u:adj[v]){
			if(u==par) continue;
			self(self,u,v);
		}
	};
	per(i,sz(adj[rt])){
		for(auto v:rbts[i]){
			if(!usd[v]){
				st.erase(st.find(v));
			}
		}
		int u=adj[rt][i];
		ask(ask,u,rt);
		for(auto v:rbts[i]){
			if(!usd[v]){
				st.insert(v);
			}
		}		
	}
	assert(sz(st));
	ert1[*st.begin()]=rt;
	cout<<ans<<" "<<ans1<<"\n";
	rep(i,n){
		cout<<ert[i]+1<<" ";
	}
	print();
	rep(i,n){
		cout<<ert1[i]+1<<" ";
	}
}

• Subtask 1: 12 / 12
• Subtask 2: 0 / 38
• Subtask 3: 0 / 50