Submission #1236719

#	Time	Username	Problem	Language	Result	Execution time	Memory
1236719		nickolasarapidis	Race (IOI11_race)	C++20	100 / 100	347 ms	79720 KiB

race

#include "race.h"
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define F first
#define S second

const int MAXN = 200000;

int k, ans = MAXN + 5;
vector<pair<int, int>> adj[MAXN];

map<int, int> m[MAXN];

void dfs(int s, int e, int d1, int d2){
	m[s][d2] = d1;
	for(auto a : adj[s]){
		int u = a.F, w = a.S;
		if(u == e) continue;
		dfs(u, s, d1 + 1, d2 + w);
		if(m[u].size() > m[s].size()) swap(m[u], m[s]);
		for(auto x : m[u]){
			if(m[s].count(2*d2 + k - x.F)) ans = min(ans, m[s][2*d2 + k - x.F] + x.S - 2*d1);
		}
		for(auto x : m[u]){
			if(m[s].count(x.F)) m[s][x.F] = min(m[s][x.F], x.S);
			else m[s][x.F] = x.S;
		}
	}
}

int best_path(int N, int K, int H[][2], int L[]){
	for(int i = 0; i < N - 1; i++){
		adj[H[i][0]].push_back({H[i][1], L[i]});
		adj[H[i][1]].push_back({H[i][0], L[i]});
	}
	k = K;
	dfs(0, -1, 0, 0);
	if(ans != MAXN + 5) return ans;
	return -1;
}

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