Submission #853640

#	Time	Username	Problem	Language	Result	Execution time	Memory
853640		Dzadzo	Race (IOI11_race)	C++17	0 / 100	5 ms	16472 KiB

race

#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define S second
#define F first
#define pii pair<ll,ll>
#define vi vector <ll>
#define vvi vector <vi>
#define vvvi vector <vvi>
#define vp vector <pii>
#define vvp vector <vp>
#define vb vector <bool>
#define vvb vector <vb>;
#define INF INT_MAX
#define MOD 998244353
#define MAXN 200000
#pragma GCC optimize("O3,unroll-loops")
using namespace std;
vvp adj(MAXN);
vb deleted(MAXN);
vi s(MAXN);
ll k;
void up(ll v,ll p){
	if (deleted[v])s[v]=0;else{
		s[v]=1;
		for (auto& [to,w]:adj[v]){
			if (to==p)continue;
			up(to,v);
			s[v]+=s[to];
		}
	}
}
ll find(ll v,ll p,ll n){
	for (auto& [to,w]:adj[v])
		if (to!=p && !deleted[to] && s[to]>n/2)
			return find(to,v,n);
	return v;
}
vi cnt(1000001,INF);
ll ans=INF;
void add(ll v,ll p,ll dist,ll depth){
	if (dist>k)return;
	cnt[dist]=min(cnt[dist],depth);
	for (auto& [to,w]:adj[v])
		if (to!=p && !deleted[to])
			add(to,v,dist+w,depth+1);
}
void calc(ll v,ll p,ll dist,ll depth){
	if (dist>k)return;
	ans=min(ans,depth+cnt[k-dist]);
//	cout<<v<<" "<<p<<" "<<dist<<" "<<depth<<" "<<cnt[k-dist]<<"\n";
	for (auto& [to,w]:adj[v])
		if (to!=p && !deleted[to])
			calc(to,v,dist+w,depth+1);	
}
void remove(ll v,ll p,ll dist){
	if (dist>k)return;
	cnt[dist]=INF;
	for (auto& [to,w]:adj[v])
		if (to!=p && !deleted[to])
			remove(to,v,dist+w);	
}
void build(ll v){
	up(v,-1);
	ll c=find(v,-1,s[v]);
	cnt[0]=0;
	for (auto& [to,w]:adj[c]){
		if (!deleted[to]){
			add(to,c,w,1);
		}
	}
	for (auto& [to,w]:adj[c]){
		if (!deleted[to]){
			calc(to,c,w,1);
		}
	}
	for (auto& [to,w]:adj[c]){
		if (!deleted[to]){
			remove(to,c,w);
		}
	}
	deleted[c]=true;
	for (auto &[to,w]:adj[c])if (!deleted[to])build(to);
}
int best_path(int N, int K, int H[][2], int L[]){
	k=K;
	for (ll i=0;i<N-1;i++){
		adj[H[i][0]].pb({H[i][1],L[i]});
		adj[H[i][1]].pb({H[i][0],L[i]});
	}
	build(0);
	if (ans==INF)return -1;
	return ans;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57