Submission #487053

#	Time	Username	Problem	Language	Result	Execution time	Memory
487053		inksamurai	Papričice (COCI20_papricice)	C++17	50 / 110	86 ms	23064 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>;
 
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);
	multiset<int> up,lo;
	int ans=1e9;
	auto g=[&](int _a,int _b,int _c){
		ans=min(ans,max({_a,_b,_c})-min({_a,_b,_c}));
	};
	auto f=[&](int v){
		int l=chs[v];
		vi rbts={(n+l)/2,(n-l)/2};
		rep(i,2){
			int rabbit=rbts[i];
			auto it=(i==0?up.lower_bound(rabbit):lo.lower_bound(rabbit));
			auto it1=(i==0?up.lower_bound(rabbit):lo.lower_bound(rabbit));
			auto it2=(i==0?up.lower_bound(rabbit):lo.lower_bound(rabbit));
			vi candies;
			if((i==0?it!=up.end():it!=lo.end())){
				candies.pb(*it);
			}
			if((i==0?it1!=up.end():it1!=lo.end())){
				it1=next(it1);
				candies.pb(*it1);
			}
			if((i==0?it2!=up.begin():it2!=lo.begin())){
				it2=prev(it2);
				candies.pb(*it2);
			}
			for(auto x : candies){
				if(x==chs[0]) continue;
				if(i==0) g(x-l,l,n-x);
				else g(x,l,n-x-l);
			}
		}
	};
	auto dfs1=[&](auto self,int v,int par)->void{
		f(v);
		up.insert(chs[v]);
		for(auto u : adj[v]){
			if(u!=par){
				self(self,u,v);
			}
		}
		lo.insert(chs[v]);
		if(up.find(chs[v])!=up.end()) up.erase(up.find(chs[v]));
	};
	dfs1(dfs1,0,-1);
	cout<<ans<<"\n";
//	
	return 0;
}

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