75 lines
2.2 KiB
PHP
75 lines
2.2 KiB
PHP
<?php
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namespace Graphp\Algorithms\TravelingSalesmanProblem;
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use Fhaculty\Graph\Graph;
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use Fhaculty\Graph\Edge\Base as Edge;
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use Fhaculty\Graph\Set\Edges;
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use Graphp\Algorithms\MinimumSpanningTree\Kruskal as MstKruskal;
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use Graphp\Algorithms\Search\BreadthFirst as SearchDepthFirst;
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class MinimumSpanningTree extends Base4
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{
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/**
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*
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* @var Graph
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*/
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private $graph;
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public function __construct(Graph $inputGraph)
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{
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$this->graph = $inputGraph;
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}
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protected function getVertexStart()
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{
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return $this->graph->getVertices()->getVertexFirst();
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}
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protected function getGraph()
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{
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return $this->graph;
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}
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/**
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*
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* @return Edges
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*/
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public function getEdges()
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{
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$returnEdges = array();
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// Create minimum spanning tree
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$minimumSpanningTreeAlgorithm = new MstKruskal($this->graph);
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$minimumSpanningTree = $minimumSpanningTreeAlgorithm->createGraph();
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$alg = new SearchDepthFirst($minimumSpanningTree->getVertices()->getVertexFirst());
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// Depth first search in minmum spanning tree (for the eulerian path)
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$startVertex = NULL;
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$oldVertex = NULL;
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// connect vertices in order of the depth first search
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foreach ($alg->getVertices() as $vertex) {
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// get vertex from the original graph (not from the depth first search)
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$vertex = $this->graph->getVertex($vertex->getId());
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// need to clone the edge from the original graph, therefore i need the original edge
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if ($startVertex === NULL) {
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$startVertex = $vertex;
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} else {
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// get edge(s) to clone, multiple edges are possible (returns an array if undirected edge)
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$returnEdges []= $oldVertex->getEdgesTo($vertex)->getEdgeFirst();
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}
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$oldVertex = $vertex;
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}
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// connect last vertex with start vertex
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// multiple edges are possible (returns an array if undirected edge)
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$returnEdges []= $oldVertex->getEdgesTo($startVertex)->getEdgeFirst();
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return new Edges($returnEdges);
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}
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}
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