Submission #492040

#	Time	Username	Problem	Language	Result	Execution time	Memory
492040		StoRovinato	Dreaming (IOI13_dreaming)	C++17	47 / 100	118 ms	23092 KiB

dreaming

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

#define MAXN 100000

using namespace std;

typedef long long ll;

vector<pair<ll, ll>> nodi[MAXN];
vector<bool> proc;
vector<ll> dist;

void dfs(ll v, vector<ll>& gruppo)
{
	proc[v] = true;
	gruppo.push_back(v);

	for (auto [u, w]: nodi[v])
	{
		if (!proc[u])
		{
			dist[u] = dist[v] + w;
			dfs(u, gruppo);
		}
	}
}

void dfs2(ll v)
{
	proc[v] = true;

	for (auto [u, w]: nodi[v])
	{
		if (!proc[u])
		{
			dist[u] = dist[v] + w;
			dfs2(u);
		}
	}
}

bool dfs3(ll v, ll p, ll y, vector<ll>& diam)
{
	if (v == y)
		return true;

	bool ok = false;
	for (auto [u, w]: nodi[v])
	{
		if (u != p)
		{
			if (dfs3(u, v, y, diam))
			{
				ok = true;
				diam.push_back(w);
				break;
			}
		}
	}
	
	return ok;
}

vector<ll> trova_diametro(ll v)
{
	vector<ll> gruppo;
	dist[v] = 0; 
	dfs(v, gruppo);


	sort(gruppo.begin(), gruppo.end(), [&](ll a, ll b){return dist[a] > dist[b];});

	for (ll i: gruppo)
		proc[i] = false;

	ll x, y;
	x = gruppo[0];

	dist[x] = 0;
	dfs2(x);

	sort(gruppo.begin(), gruppo.end(), [&](ll a, ll b){return dist[a] > dist[b];});

	y = gruppo[0];

	vector<ll> diam;
	dfs3(x, -1, y, diam);
	return diam;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
	for (ll i = 0; i < M; i++)
	{
		nodi[A[i]].push_back({B[i], T[i]});
		nodi[B[i]].push_back({A[i], T[i]});
	}

	vector<ll> valori;
	vector<ll> diam;

	dist.resize(N, 0);
	proc.resize(N, false);
	for (ll i = 0; i < N; i++)
	{
		if (!proc[i])
		{
			vector<ll> diametro = trova_diametro(i);

			/*
			cout << "\n\n";
			for (ll i: diametro)
				cout << i << " ";
			cout << "\n\n";
			*/


			if (diametro.empty())
			{
				valori.push_back(0);
				diam.push_back(0);
				continue;
			}

			ll sx = 0, dx = 0;
			for (ll j: diametro)
				dx += j;
			ll minimo = dx;
			diam.push_back(dx);
			for (ll j = 0; j < diametro.size(); j++)
			{
				sx += diametro[j];
				dx -= diametro[j];

				minimo = min(minimo, max(sx, dx));
			}

			valori.push_back(minimo);
		}
	}

	sort(valori.begin(), valori.end());
	sort(diam.begin(), diam.end());

	return max(diam.back(), valori.back() + valori[valori.size() - 2] + L);

	if (valori.size() == 1)
		return diam[0];
	if (valori.size() == 2)
		return max(diam[1], valori[0] + valori[1] + L);
	if (valori.size() > 2)
		return max(max(diam.back(), valori.back() + valori[valori.size() - 2] + L), valori[valori.size() - 2] + valori[valori.size() - 3] + 2 * L);
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:131:21: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  131 |    for (ll j = 0; j < diametro.size(); j++)
      |                   ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23