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<?php |
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namespace drupol\phpermutations; |
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/** |
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* Class Permutations. |
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* |
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* @package drupol\phpermutations |
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*/ |
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class Permutations extends Combinatorics { |
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/** |
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* Permutations constructor. |
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* |
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* @param array $dataset |
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* @param int $length |
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*/ |
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public function __construct(array $dataset = array(), $length = NULL) { |
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parent::__construct($dataset, $length); |
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} |
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/** |
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* @return int |
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*/ |
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public function count() { |
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return $this->fact(count($this->getDataset())) / $this->fact(count($this->getDataset()) - $this->getLength()); |
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} |
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/** |
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* @return \Generator |
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*/ |
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public function generator() { |
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$combinations = new Combinations($this->getDataset(), $this->getLength()); |
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$result = array(); |
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foreach ($combinations->toArray() as $subset) { |
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$set = $subset; |
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$perms = array(); |
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$size = count($subset) - 1; |
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$perm = range(0, $size); |
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$j = 0; |
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do { |
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foreach ($perm as $i) { |
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$perms[$j][] = $set[$i]; |
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} |
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} while ($perm = $this->permute($perm, $size) and ++$j); |
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$result = array_merge($result, $perms); |
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} |
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return $result; |
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} |
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/** |
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* @param $items |
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* @param array $perms |
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* |
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* @return array |
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*/ |
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protected function permute($p, $size) { |
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// slide down the array looking for where we're smaller than the next guy |
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for ($i = $size - 1; $i >= 0 && $p[$i] >= $p[$i+1]; --$i) { } |
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// if this doesn't occur, we've finished our permutations |
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// the array is reversed: (1, 2, 3, 4) => (4, 3, 2, 1) |
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if ($i == -1) { |
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return false; |
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} |
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// slide down the array looking for a bigger number than what we found before |
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for ($j = $size; $p[$j] <= $p[$i]; --$j) { } |
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// swap them |
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$tmp = $p[$i]; $p[$i] = $p[$j]; $p[$j] = $tmp; |
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// now reverse the elements in between by swapping the ends |
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for (++$i, $j = $size; $i < $j; ++$i, --$j) { |
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$tmp = $p[$i]; $p[$i] = $p[$j]; $p[$j] = $tmp; |
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} |
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return $p; |
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} |
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/** |
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* @return array |
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*/ |
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public function toArray() { |
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$results = array(); |
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foreach ($this->generator() as $value) { |
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$results[] = $value; |
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} |
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return $results; |
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} |
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} |
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This check looks for
@param
annotations where the type inferred by our type inference engine differs from the declared type.It makes a suggestion as to what type it considers more descriptive.
Most often this is a case of a parameter that can be null in addition to its declared types.