Submission #487047

#	Time	Username	Problem	Language	Result	Execution time	Memory
487047		inksamurai	Papričice (COCI20_papricice)	C++17	50 / 110	389 ms	23132 KiB

papricice

#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(),a.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define crep(i,x,n) for(int i=x;i<n;i++)
#define drep(i,n) for(int i=n-1;i>=0;i--)
#define vec(...) vector<__VA_ARGS__>
#define _322ZVFH ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
using pii=pair<int,int>;
using vi=vector<int>;

struct treelca{
	int n;
	int timer=0;
	vec(vi) adj;
	vi tin,tout,tour,tourid;
	vi segtree;
	vi depth;
	treelca(int m,int root,vec(vi) neadj){
		init(m,root,neadj);
	}
	void init(int m,int root,vec(vi) neadj){
		n=m;
		tin.clear();
		tout.clear();
		tour.clear();
		tourid.clear();
		depth.clear();
		tin.resize(n,0);
		tout.resize(n,0);
		tourid.resize(n,0);
		depth.resize(n,0);
		adj=neadj;
		dfs(root,-1);
		segtree.resize(4*sz(tour));
		build(1,0,sz(tour)-1);
	}
	void dfs(int v,int par){
		tour.pb(v);
		tourid[v]=sz(tour)-1;
		tin[v]=timer++;
		for(auto u : adj[v]){
			if(u==par) continue;
			depth[u]=depth[v]+1;
			dfs(u,v);
			tour.pb(v);
		}
		tout[v]=timer++;
	}
	void build(int node,int l,int r){
		if(l==r){
			segtree[node]=tour[l];
		}else{
			int m=(l+r)>>1;
			build(node*2,l,m);
			build(node*2+1,m+1,r);
			segtree[node]=(tin[segtree[node*2]]<tin[segtree[node*2+1]]?segtree[node*2]:segtree[node*2+1]);
		}
	}
	int query(int node,int l,int r,int _l,int _r){
		if(l>_r or r<_l) return -1;
		if(l>=_l and r<=_r) return segtree[node];
		int m=(l+r)>>1;
		int vl=query(node*2,l,m,_l,_r);
		int vr=query(node*2+1,m+1,r,_l,_r);
		if(min(vl,vr)==-1) return max(vl,vr);
		return (tin[vl]<tin[vr]?vl:vr);
	}
	int ancestor(int from,int to){
		int tinfrom=tin[from],tinto=tin[to];
		if(tinfrom>tinto) swap(tinfrom,tinto);
		return query(1,0,sz(tour)-1,tinfrom,tinto);
	}
	int dist(int u,int v){
		return depth[u]+depth[v]-depth[ancestor(u,v)]*2;
	}
};

int main(){
_322ZVFH;
	int n;
	cin>>n;
	vec(vi) adj(n);
	rep(i,n-1){
		int u,v;
		cin>>u>>v;
		u--,v--;
		adj[u].pb(v);
		adj[v].pb(u);
	}
	assert(n<=2000);
	vi chs(n,0);
	auto dfs=[&](auto self,int v,int par)->void{
		chs[v]=1;
		for(auto u : adj[v]){
			if(u!=par){
				self(self,u,v);
				chs[v]+=chs[u];
			}
		}
	};
	dfs(dfs,0,-1);
	treelca lca(n,0,adj);
	int ans=1e9;
	rep(v,n){
		crep(u,v+1,n){
			int up=lca.ancestor(u,v);
			vi candies;
			int l=chs[v],r=chs[u];
			if(l>r) swap(l,r);
			if(up==v or up==u){
				
				candies={l,r-l,n-r};
				ans=min(ans,*max_element(all(candies))-*min_element(all(candies)));
			}else{
				candies={l,r,n-l-r};
				ans=min(ans,max({r-l,n-r-2*l,2*r+l-n}));
			}
			// ans=min(ans,*max_element(all(candies))-*min_element(all(candies)));
		}
	}
	cout<<ans<<"\n";
//	
	return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 0 / 60