Submission #305757

#	Time	Username	Problem	Language	Result	Execution time	Memory
305757		Temmie	Dreaming (IOI13_dreaming)	C++17	100 / 100	139 ms	19064 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"

std::vector <std::vector <std::pair <int, int>>> g;
std::vector <std::pair <int, int>> d1, d2;
std::vector <int> d;

std::vector <bool> vis;

void dfs1(int node, int par) {
	vis[node] = true;
	for (auto p : g[node]) if (p.first != par) {
		int x = p.first, w = p.second;
		dfs1(x, node);
		d2[node] = std::max(d2[node], { d1[x].first + w, x });
		if (d2[node] > d1[node]) std::swap(d1[node], d2[node]);
	}
}

std::vector <int> nows;
void dfs2(int node, int par, int dist) {
	vis[node] = true;
	nows.push_back(node);
	d[node] = std::max(d1[node].first, dist);
	for (auto p : g[node]) if (p.first != par) {
		int x = p.first, w = p.second;
		if (x == d1[node].second) dfs2(x, node, std::max(d2[node].first, dist) + w);
		else dfs2(x, node, d[node] + w);
	}
}

bool comp(const int& a, const int& b) {
	return d[a] < d[b];
}

int travelTime(int n, int m, int l, int a[], int b[], int t[]) {
	g.resize(n);
	d1.resize(n);
	d2.resize(n);
	d.resize(n);
	for (int i = 0; i < m; i++) {
		g[a[i]].push_back({ b[i], t[i] });
		g[b[i]].push_back({ a[i], t[i] });
	}
	vis.resize(n, false);
	for (int i = 0; i < n; i++) {
		if (!vis[i]) {
			dfs1(i, -1);
		}
	}
	vis.clear();
	vis.resize(n, false);
	std::vector <int> ws;
	for (int i = 0; i < n; i++) {
		if (!vis[i]) {
			dfs2(i, -1, 0);
			std::sort(nows.begin(), nows.end(), comp);
			ws.push_back(d[nows[0]]);
			nows.clear();
		}
	}
	std::sort(ws.rbegin(), ws.rend());
	int maxdia = 0;
	for (int x : d) maxdia = std::max(maxdia, x);
	if (ws.size() == size_t(1)) return maxdia;
	if (ws.size() == size_t(2)) return std::max(maxdia, ws[0] + ws[1] + l);
	return std::max({ ws[0] + ws[1] + l, ws[1] + ws[2] + l + l, maxdia });
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23