Submission #738404

#	Time	Username	Problem	Language	Result	Execution time	Memory
738404		Baytoro	경주 (Race) (IOI11_race)	C++17	100 / 100	434 ms	101492 KiB

race

#include "race.h"
//#include "grader.cpp"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define fr first
#define sc second
#define all(x) x.begin(),x.end()
const ll NN=2e5+5;
vector<pair<int,int>> g[NN];
ll ans=1e9,k;
map<ll,ll> mp[NN];
void dfs(int x, int p, ll d, int depth){
	mp[x][d]=depth;
	for(auto it: g[x]){
		if(it.fr==p) continue;
		dfs(it.fr,x,d+it.sc,depth+1);
		if(mp[x].size()<mp[it.fr].size()) 
			swap(mp[x],mp[it.fr]);
		for(auto i: mp[it.fr]){
			ll target=k-i.fr+2*d;
			if(mp[x].find(target)!=mp[x].end()){
				ans=min(ans,mp[x][target]+i.sc-2*depth);
			}
		}
		for(auto i: mp[it.fr]){
			if(mp[x].find(i.fr)==mp[x].end()){
				mp[x].insert(i);
			}
			else{
				mp[x][i.fr]=min(mp[x][i.fr],i.sc);
			}
		}
	}
}
int best_path(int N, int K, int H[][2], int L[]){
	k=K;
	ans=N;
	for(int i=0;i<N-1;i++){
		int a=H[i][0],b=H[i][1],c=L[i];
		g[a].pb({b,c});
		g[b].pb({a,c});
	}
	dfs(0,-1,0,0);
	if(ans==N) ans=-1;
	return ans;
}

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