Submission #547484

#	Time	Username	Problem	Language	Result	Execution time	Memory
547484		blue	Toy Train (IOI17_train)	C++17	100 / 100	716 ms	1792 KiB

train

#include "train.h"
#include <vector>
#include <queue>
#include <algorithm>
#include <iostream>
using namespace std;

using vi = vector<int>;
#define sz(x) int(x.size())

const int mx = 5'000;

vi edge[mx];
vi revedge[mx];

int n, m;
vi a, r;

vi getforced(vi active, vi good, int player)
{
	// cerr << "\n\n\n\nCALLED\n";
	vi deg(n, 0);
	for(int i = 0; i < n; i++)
	{
		if(!active[i]) continue;
		for(int j : edge[i])
		{
			if(active[j])
				deg[i]++;
		}
	}

	queue<int> tbv;
	for(int i = 0; i < n; i++)
	{
		// cerr << i << " -> " << active[i] << ' ' << good[i] << '\n';
		if(active[i] && good[i])
		{
			tbv.push(i);
		}
	}

	while(!tbv.empty())
	{
		int u = tbv.front();
		tbv.pop();
		// cerr << "u = " << u << '\n';

		for(int v : revedge[u])
		{
			if(!active[v]) continue;
			if(good[v]) continue;

			// cerr << v << " : " << a[v] << ' ' << player << '\n';

			if(a[v] == player)
			{
				good[v] = 1;
				tbv.push(v);
			}
			else
			{
				deg[v]--;
				if(deg[v] == 0)
				{
					good[v] = 1;
					tbv.push(v);
				}
			}
		}
	}

	return good;
}


 //a = owner, r = charging
vi who_wins(vi a_, vi r_, vi U, vi V) 
{
	a = a_;
	r = r_;
	n = sz(a);
	m = sz(U);


	for(int j = 0; j < m; j++)
	{
		edge[U[j]].push_back(V[j]);
		revedge[V[j]].push_back(U[j]);
	}


	vi active(n, 1);

	while(1)
	{
		// cerr << "it\n";
		int oldcount = 0;
		for(int i = 0; i < n; i++) oldcount += active[i];

		vi stations(n, 0);
		for(int i = 0; i < n; i++) stations[i] = active[i] && r[i];

		// cerr << "stations = ";
		// cerr << stations[0] << ' ' << stations[1] << '\n';


		vi Areach = getforced(active, stations, 1);

		// cerr << "Areach = ";
		// cerr << Areach[0] << ' ' << Areach[1] << '\n';

		vi nonAreach(n);
		for(int i = 0; i < n; i++)
		{
			if(!active[i])
				nonAreach[i] = 0;
			else
				nonAreach[i] = !Areach[i];
		}
		// cerr << nonAreach[0] << ' ' << nonAreach[1] << '\n';

		vi Breach = getforced(active, nonAreach, 0);

		for(int i = 0; i < n; i++)
			if(Breach[i])
				active[i] = 0;

		// cerr << Breach[0] << ' ' << Breach[1] << '\n';

		int newcount = 0;
		for(int i = 0; i < n; i++) newcount += active[i];

		// cerr << oldcount << " : " << newcount << '\n';

		// for(int i = 0; i < n; i++) cerr << active[i] << ' ';
		// 	cerr << '\n';

		if(oldcount == newcount) break;
	}

	return active;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 11 / 11
• Subtask 4: 11 / 11
• Subtask 5: 12 / 12
• Subtask 6: 51 / 51