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<?php |
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namespace TemplesOfCode\NodesAndEdges\DFS; |
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use InvalidArgumentException; |
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use TemplesOfCode\NodesAndEdges\Graph; |
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/** |
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* Class DepthFirstSearch |
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* @package TemplesOfCode\NodesAndEdges\DFS |
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*/ |
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class DepthFirstSearch |
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{ |
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/** |
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* @var bool[] |
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*/ |
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protected $marked; |
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/** |
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* @var Graph |
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*/ |
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protected $graph; |
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/** |
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* @var int |
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*/ |
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private $count; |
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/** |
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* DepthFirstSearch constructor. |
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* @param Graph $graph |
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* @param int $sourceVertex |
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*/ |
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public function __construct(Graph $graph, int $sourceVertex) |
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{ |
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// validate this vertex in the context of the given graph |
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Graph::validateVertex($sourceVertex, $graph->getVertices()); |
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// set |
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$this->graph = $graph; |
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// set |
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$this->marked = array_fill(0, $graph->getVertices(), false); |
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// execute DFS logic |
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$this->dfs($sourceVertex); |
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} |
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/** |
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* Is there a path between the source vertex and vertex v |
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* |
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* @param int $vertex |
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* @return bool true if there is a path, false otherwise |
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* @throws InvalidArgumentException unless 0 <= $vertex < $vertices |
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*/ |
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public function marked(int $vertex) { |
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// convenience var |
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$vertices = $this->graph->getVertices(); |
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// validate this vertex in the context of the given graph |
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Graph::validateVertex($vertex, $vertices); |
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// return the flag |
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return $this->marked[$vertex]; |
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} |
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/** |
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* @param int $vertex |
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*/ |
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protected function dfs(int $vertex) |
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{ |
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// bump up |
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$this->count++; |
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// mark the visit |
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$this->marked[$vertex] = true; |
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// get neighbors |
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$neighbors = $this->graph->adjacent($vertex); |
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// iterate over the set |
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foreach ($neighbors as $w) { |
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// check for previous visit |
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if (!$this->marked[$w]) { |
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// has not been visited yet |
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$this->dfs($w); |
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} |
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} |
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} |
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/** |
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* Returns the number of vertices connected to $sourceVertex |
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* |
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* @return int the number of vertices connected to $sourceVertex |
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*/ |
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public function count() |
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{ |
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return $this->count; |
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} |
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} |
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templesofcode /
nodes-and-edges
