Cod sursa(job #2784957)

Utilizator SteFUNGrigorescu Stefan Dumitru SteFUN Data 17 octombrie 2021 19:09:20
Problema BFS - Parcurgere in latime Scor 80
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.3 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <unordered_map>
#include <queue>

//std::ifstream f("graful.txt");
//std::ofstream g("graful.out");
std::ifstream f("bfs.in");
std::ofstream g("bfs.out");

int start = 0;
class graf
{
	int nrvf, nrmuchii;
	std::unordered_map < int, std::vector< int > > vecini;

public:
	void creaza_muchie(int start, int finish);

	graf(bool orientat);

	void verifvecini();

	void BFS(int nod, std::queue <int> qBFS, int* dist);   //  pas se va adauga la dist[nod]
	void cadruBFS();
};

void graf::creaza_muchie(int start, int finish)
{
	if (vecini.find(start) != vecini.end())
		vecini[start].push_back(finish);
	else
	{
		std::vector < int > vaux;
		vaux.push_back(finish);
		std::pair < int, std::vector < int > > paux(start, vaux);
		vecini.insert(paux);
	}
}

graf::graf(bool orientat)
{
	f >> nrvf >> nrmuchii;
	if(start == 1)	// daca avem de citit un nod de start...
		f >> start;

	if (orientat == true)
		for (int i = 0; i < nrmuchii; i++)
		{
			int x, y;
			f >> x >> y;
			creaza_muchie(x, y);
		}
	else
		for (int i = 0; i < nrmuchii; i++)
		{
			int x, y;
			f >> x >> y;
			creaza_muchie(x, y);
			creaza_muchie(y, x);
		}
}

void graf::verifvecini()
{
	for (int i = 1; i <= nrvf; i++)
	{
		std::cout << "\n  vecinii lui " << i << " :  ";
		for (unsigned int j = 0; j < vecini[i].size(); j++)
			std::cout << vecini[i][j] << " ";
	}
}

//void graf::BFS(int nod, std::queue <int> qBFS, int* dist)
//{
//
//	if (!qBFS.empty())
//		BFS(qBFS.front(), qBFS, dist);
//}

void graf::cadruBFS()
{
	int* dist = new int[nrvf + 1]{ 0 };	// initializam distantele cu 0 (le decrementam ulterior)
	std::queue <int> qBFS;	  // coada pt BFS
	qBFS.push(start);
	dist[start] = 1;

	/*BFS(start, qBFS, dist);*/

	while (!qBFS.empty())
	{
		const int nod = qBFS.front();
		for (unsigned int i = 0; i < vecini[nod].size(); i++)
		{
			const int nod_urm = vecini[nod][i];
			if (dist[nod_urm] == 0)
			{
				qBFS.push(nod_urm);
				dist[nod_urm] = dist[nod] + 1;
			}
		}

		qBFS.pop();
	}


	for (int i = 1; i <= nrvf; i++)
	{
		g << dist[i] - 1 << " ";
	}
	delete [] dist;
}

int main()
{
	start = 1;		// afirmam ca citim si un nod de start;
	graf g(true);
	g.cadruBFS();

	return 0;
}