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<?php |
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namespace Algorithms; |
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class Dijkstra |
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{ |
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protected $points = array(); |
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protected $relations; |
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protected $generated = null; |
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public function __construct($relations = null) |
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{ |
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if (!empty($relations)) { |
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$this->setRelations($relations); |
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} |
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} |
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public function setRelations($relations) |
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{ |
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if (self::validate($relations)) { |
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$this->relations = $relations; |
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} else { |
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if (is_callable($relations) && ($relations instanceof \Closure)) { |
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$creator = new GraphTools\Creator; |
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call_user_func($relations, $creator); |
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$this->relations = $creator->createConnections(); |
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} |
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} |
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} |
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public function generate() |
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{ |
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return DijkstraCache::loadMany($this->generated, function () { |
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$results = []; # Prepare results array |
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# Analyze all relations |
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foreach ($this->relations as $point => $relation) { |
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$results[$point] = DijkstraCache::loadOne($this->generated, $point, function () use ($point) { |
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return $this->distances($point); |
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}); |
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} |
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return $results; |
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}); |
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} |
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private function init($point) |
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{ |
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$this->points = array(); |
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$this->points[$point] = DijkstraCache::loadOne($this->generated, $point, function () { |
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return array(0, ''); |
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}); |
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} |
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private function dist($source, $pointId, &$visited = []) |
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{ |
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$visited[$pointId] = true; # Set current point as visited |
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# Prepare help variables |
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$min_ptr = -1; |
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$min = 0; |
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# Analyzes point neighborhood |
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foreach ($this->relations[$pointId] as $relation) { |
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if ($relation[0] != $source) { # If current point is different than source |
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list($min_ptr, $min) = $this->setMinPtr($relation, $visited, $min_ptr, $min); |
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# Change the shortest way to current point |
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$distance = $this->getShortestDistance($pointId); |
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$this->updatePoint($pointId, $relation, $distance); |
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} |
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} |
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# If isset unvisited point with minimal way go for it |
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if ($min_ptr != -1) { |
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$this->dist($source, $min_ptr, $visited); |
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} |
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} |
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private function getShortestDistance($pointId) |
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{ |
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return isset($this->points[$pointId][0]) ? $this->points[$pointId][0] : 0; |
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} |
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private function setMinPtr($relation, $visited, $min_ptr, $min) |
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{ |
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if (empty($visited[$relation[0]])) { # If current point is not visited |
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if ($min_ptr == -1) { # When minimal point is not finded |
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$min_ptr = $relation[0]; |
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$min = $relation[1]; |
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} elseif ($min > $relation[1]) { |
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$min_ptr = $relation[0]; |
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$min = $relation[1]; |
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} |
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} |
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return array($min_ptr, $min); |
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} |
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private function updatePoint($pointId, $relation, $distance) |
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{ |
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if (empty($this->points[$relation[0]])) { |
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$this->points[$relation[0]] = [ |
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$distance + $relation[1], |
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((empty($this->points[$pointId][1])) ? $pointId : $this->points[$pointId][1]) . ':' . $relation[0], |
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]; |
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} else { |
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if ($this->points[$relation[0]][0] > ($this->points[$pointId][0] + $relation[1])) { |
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$this->points[$relation[0]] = [ |
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(isset($this->points[$pointId][0]) ? $this->points[$pointId][0] : 0) + $relation[1], |
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(empty($this->points[$pointId][1]) ? null : $this->points[$pointId][1] . ':') . $relation[0], |
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]; |
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} |
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} |
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} |
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public function distances($point) |
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{ |
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return DijkstraCache::loadOne($this->generated, $point, function () use ($point) { |
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$this->init($point); |
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$this->dist($point, $point); |
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return $this->points; |
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}); |
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} |
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public static function validate($relations_array) |
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{ |
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$return = is_array($relations_array); |
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if ($return) { |
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foreach ($relations_array as $relations) { |
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$return &= self::checkPointRelations($relations); |
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} |
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} |
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return $return; |
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} |
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private static function checkPointRelations($relations) |
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{ |
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$return = is_array($relations); |
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if ($return) { |
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foreach ($relations as $relation) { |
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$return &= self::checkSingleRelation($relation); |
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} |
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} |
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return $return; |
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} |
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private static function checkSingleRelation($relation) |
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{ |
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return (is_array($relation) && (count($relation) == 2) && isset($relation[0]) && isset($relation[1])); |
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} |
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} |
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PHPAlgorithms /
Dijkstra-s-algorithm
