/**
*
* @return Edges
*/
public function getEdges()
{
$returnEdges = array();
// Create minimum spanning tree
$minimumSpanningTreeAlgorithm = new MstKruskal($this->graph);
$minimumSpanningTree = $minimumSpanningTreeAlgorithm->createGraph();
$alg = new SearchDepthFirst($minimumSpanningTree->getVertices()->getVertexFirst());
// Depth first search in minmum spanning tree (for the eulerian path)
$startVertex = NULL;
$oldVertex = NULL;
// connect vertices in order of the depth first search
foreach ($alg->getVertices() as $vertex) {
// get vertex from the original graph (not from the depth first search)
$vertex = $this->graph->getVertex($vertex->getId());
// need to clone the edge from the original graph, therefore i need the original edge
if ($startVertex === NULL) {
$startVertex = $vertex;
} else {
// get edge(s) to clone, multiple edges are possible (returns an array if undirected edge)
$returnEdges[] = $oldVertex->getEdgesTo($vertex)->getEdgeFirst();
}
$oldVertex = $vertex;
}
// connect last vertex with start vertex
// multiple edges are possible (returns an array if undirected edge)
$returnEdges[] = $oldVertex->getEdgesTo($startVertex)->getEdgeFirst();
return new Edges($returnEdges);
}
/**
*
*
* @param Vertex $source
* @throws Exception if there is no reachable sink vertex
*
* @return Vertex a sink-vertex that is reachable from the source
* @uses BreadthFirst::getVertices()
*/
private function getVertexSink(Vertex $source)
{
// search for reachable Vertices
$algBFS = new SearchBreadthFirst($source);
foreach ($algBFS->getVertices()->getMap() as $vid => $vertex) {
if ($this->graph->getVertex($vid)->getBalance() - $vertex->getBalance() < 0) {
return $vertex;
}
}
throw new UnderflowException('No sink vertex connected to given source vertex found');
}
