Submission #1309205

#	Time	Username	Problem	Language	Result	Execution time	Memory
1309205		JuanJL	Race (IOI11_race)	C++20	9 / 100	57 ms	17380 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define fst first
#define snd second
#define pb push_back
#define forn(i,a,b) for(int i = a; i<b; i++)
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(),x.end()
#define mset(a,v) memset(a,v,sizeof(a))
#define FIN ios::sync_with_stdio(0); cout.tie(); cin.tie(0);
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
template <typename L>
using iset = tree<L,null_type,less<L>,rb_tree_tag,tree_order_statistics_node_update>;

const int MAXN = 200000+5;

ll n;
ll k;
vector<pair<ll,ll>> adj[MAXN];
vector<pair<ll,ll>> nadj[MAXN];
ll realv[MAXN];
ll rres = 1000000000;

void dfs(ll nd, ll p,ll dep, ll sz, unordered_map<ll,ll> &path){

	//cout<<"ND "<<nd<<"----------------\n";
	for(auto i:adj[nd]) if(i.fst!=p){
		
		unordered_map<ll,ll> pathc;
		dfs(i.fst,nd,dep+1,sz+i.snd,pathc);
		//cout<<i.fst<<": "; for(auto j:pathc) cout<<j.fst<<" "<<j.snd<<" || "; cout<<'\n';

		if(SZ(pathc)>SZ(path)) swap(pathc,path);

		for(auto [szchild,rdep]:pathc){
			if(path.find(k-szchild+sz)!=path.end()){
				rres=min(rres,rdep-dep+path[k-szchild+sz]-dep);
			}
		}

		for(auto [szchild,rdep]:pathc){
			if(path.find(szchild)==path.end()){
				path[szchild]=rdep;
			}else{
				path[szchild]=min(path[szchild],rdep);
			}
		}
		//cout<<"New path de "<<i.fst<<": "; for(auto j:path) cout<<j.fst<<" "<<j.snd<<" |||| "; cout<<'\n';
	}

	if(path.find(sz+k)!=path.end()){
		rres=min(rres,path[sz+k]-dep);
	}
	path[sz]=dep;
}


void opti(ll nd, ll p,ll &aux){
	realv[nd]=aux;
	for(auto i:nadj[nd])if(i.fst!=p){
		aux++;
		opti(i.fst,nd,aux);
	}
}

int best_path(int N, int K, int H[][2], int L[]){
	//cout<<"inica\n";
	FIN;
	n = N;
	k = K;
	forn(i,0,n-1){
		nadj[H[i][0]].pb({H[i][1],L[i]});
		nadj[H[i][1]].pb({H[i][0],L[i]});
	}

	ll aux = 0;
	opti(0,-1,aux);
	forn(i,0,n-1){
		adj[realv[H[i][0]]].pb({realv[H[i][1]],L[i]});
		adj[realv[H[i][1]]].pb({realv[H[i][0]],L[i]});
	}

	unordered_map<ll,ll> path;
	dfs(0,-1,0,0,path);
	

  	return (rres!=1000000000?rres:-1);
}

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