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<?php |
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namespace App\Component\Math\Graph\Path; |
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/** |
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* Dijikstra path search for weighted graph |
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* |
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*/ |
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class Weight |
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{ |
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const _INF = 99999; |
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/** |
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* graph |
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* |
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* @var array |
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*/ |
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protected $graph; |
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/** |
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* source |
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* |
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* @var String |
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*/ |
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private $src; |
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/** |
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* destination |
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* |
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* @var String |
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*/ |
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private $dst; |
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/** |
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* path |
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* |
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* @var array |
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*/ |
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private $path = []; |
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/** |
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* the nearest path with its parent and weight |
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* |
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* @var array |
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*/ |
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private $s = []; |
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/** |
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* the left nodes without the nearest path |
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* |
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* @var array |
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*/ |
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private $q = []; |
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/** |
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* __construct |
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* |
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* @param array $graph |
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*/ |
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public function __construct($graph) |
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{ |
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$this->graph = $graph; |
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} |
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/** |
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* path |
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* |
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* @param string $src |
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* @param string $dst |
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* @return array |
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*/ |
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1 |
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public function path(string $src, string $dst): array |
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{ |
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$this->init($src, $dst); |
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$this->path = []; |
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if (isset($this->graph[$this->src]) && isset($this->graph[$this->dst])) { |
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1 |
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$this->search()->processPath(); |
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} |
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return $this->path; |
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} |
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/** |
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* distance |
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* |
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* @return float |
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*/ |
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public function distance(): float |
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{ |
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return ($this->path) ? $this->s[$this->dst][1] : 0; |
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} |
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/** |
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* start calculating |
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* |
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* @return Weight |
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*/ |
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1 |
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protected function search(): Weight |
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{ |
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1 |
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while (!empty($this->q)) { |
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1 |
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$min = $this->min(); |
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1 |
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if ($min == $this->dst) { |
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1 |
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break; |
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} |
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1 |
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$keys = array_keys($this->graph[$min]); |
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1 |
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$kam = count($keys); |
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1 |
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for ($c = 0; $c < $kam; $c++) { |
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$k = $keys[$c]; |
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$v = $this->graph[$min][$k]; |
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if (!empty($this->q[$k])) { |
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if (($checkMin = $this->q[$min] + $v) < $this->q[$k]) { |
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$this->q[$k] = $checkMin; |
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$this->s[$k] = [$min, $this->q[$k]]; |
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} |
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} |
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} |
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1 |
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unset($this->q[$min]); |
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} |
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return $this; |
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} |
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/** |
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* lowest weighted node name |
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* |
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* @return string |
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*/ |
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1 |
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protected function min(): string |
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{ |
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return array_search(min($this->q), $this->q); |
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} |
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/** |
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* init queue assuming all edges are bi-directional |
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* |
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* @param string $src |
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* @param string $dst |
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* @return Weight |
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*/ |
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protected function init(string $src, string $dst): Weight |
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{ |
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$this->src = $src; |
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$this->dst = $dst; |
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1 |
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$this->s = []; |
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1 |
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$this->q = []; |
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1 |
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$keys = array_keys($this->graph); |
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1 |
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foreach ($keys as $key) { |
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$this->q[$key] = self::_INF; |
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} |
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1 |
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$this->q[$this->src] = 0; |
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1 |
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return $this; |
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} |
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/** |
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153
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* set path |
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* |
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* @return Weight |
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*/ |
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1 |
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protected function processPath(): Weight |
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{ |
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$this->path = []; |
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$pos = $this->dst; |
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while ($pos != $this->src) { |
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$this->path[] = $pos; |
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$pos = $this->s[$pos][0]; |
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} |
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$this->path[] = $this->src; |
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$this->path = array_reverse($this->path); |
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return $this; |
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} |
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169
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} |
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pierre-fromager /
nymfonya
