Cod sursa(job #535538)

Utilizator nahsucpasat cristian nahsuc Data 17 februarie 2011 13:42:38
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.15 kb
// http://infoarena.ro/problema/bfs
#include <fstream>
#include <vector>
#include <list>
#include <queue>
using namespace std;

int nodes,edges,startNode;
vector< list<int> > graph;
vector<int> visited;
queue<int> myQueue;

void read();
void breadthFirst(int startNode);
void write();

int main() {
	read();
	breadthFirst(startNode);
	write();

	return (0);
}

void read() {
	ifstream in("bfs.in");
	int from,to;

	in >> nodes >> edges >> startNode;
	graph.resize(nodes+1);
	visited.resize(nodes+1);

	for(int i=1;i<=edges;i++) {
		in >> from >> to;

		if(from != to)
			graph.at(from).push_back(to);
	}

	in.close();
}

void breadthFirst(int startNode) {
	int node;
	myQueue.push(startNode);
	visited.at(startNode) = 1;

	while(!myQueue.empty())
	{
		node = myQueue.front();
		myQueue.pop();

		for(list<int>::iterator it=graph.at(node).begin();it!=graph.at(node).end();it++)
			if(!visited.at(*it))
			{
				myQueue.push(*it);
				visited.at(*it) = visited.at(node) + 1;
			}
	}
}

void write() {
	ofstream out("bfs.out");

	for(int i=1;i<=nodes;i++)
		out << visited.at(i) - 1 << " ";

	out.close();
}