제출 #412803

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
412803		nichke	경주 (Race) (IOI11_race)	C++14	100 / 100	1437 ms	49752 KiB

race

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

int ans = INT_MAX;
int sz[200005];
vector<pair<int, int>> adj[200005];
bool removed[200005];

void dfssz(int v, int par = -1) {
	sz[v] = 1;
	for (auto u : adj[v]) {
		if (u.first == par) continue;
		if (removed[u.first]) continue;
		dfssz(u.first, v);
		sz[v] += sz[u.first];
	}
}

int centroid(int v, int full, int par = -1) {
	for (auto u : adj[v]) {
		if (u.first == par) continue;
		if (removed[u.first]) continue;
		if (sz[u.first] * 2 > full) {
			return centroid(u.first, full, v);
		}
	}
	return v;
}

void update(map<int, int>& mp, map<int, int>& mp2, int len, int val, int K) {
	if (mp2.find(len) == mp2.end()) mp2[len] = val;
	else mp2[len] = min(mp2[len], val);
	if (mp.find(K - len) != mp.end()) ans = min(ans, mp2[len] + mp[K - len]);
}

void solve(int v, map<int, int> &mp, map<int, int> &mp2, int len, int K, int depth, int par) {
	for (auto u : adj[v]) {
		if (u.first == par) continue;
		if (removed[u.first]) continue;
		if (len + u.second <= K) {
			update(mp, mp2, len + u.second, 1 + depth, K);
			solve(u.first, mp, mp2, len + u.second, K, depth + 1, v);
		}
	}
}

void decompose(int v, int K) {
	dfssz(v);
	int c = centroid(v, sz[v]);
	map<int, int> mp;
	for (auto u : adj[c]) {
		if (removed[u.first]) continue;
		if (u.second > K) continue;
		map<int, int> mp2;
		update(mp, mp2, u.second, 1, K);
		solve(u.first, mp, mp2, u.second, K, 1, c);
		for (auto it : mp2) {
			if (mp.find(it.first) != mp.end()) mp[it.first] = min(mp[it.first], it.second);
			else mp[it.first] = it.second;
		}
	}
	if (mp.find(K) != mp.end()) ans = min(ans, mp[K]);
	removed[c] = 1;
	for (auto u : adj[c]) {
		if (removed[u.first]) continue;
		decompose(u.first, K);
	}
}

int best_path(int N, int K, int H[][2], int L[]) {
	for (int i = 0; i < N - 1; i++) {
		int u = H[i][0], v = H[i][1];
		adj[u].push_back({v, L[i]});
		adj[v].push_back({u, L[i]});
	}
	decompose(0, K);
	if (ans != INT_MAX) return ans;
	return -1;
}

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