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<?php |
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declare(strict_types=1); |
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namespace CoenMooij\Sudoku\Validator; |
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use CoenMooij\Sudoku\Exception\UnsolvableException; |
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use CoenMooij\Sudoku\Puzzle\Grid; |
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use CoenMooij\Sudoku\Puzzle\Location; |
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use CoenMooij\Sudoku\Solver\BacktrackSolver; |
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class DigValidator |
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{ |
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/** |
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* @var BacktrackSolver |
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*/ |
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private $solver; |
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public function __construct(BacktrackSolver $solver) |
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{ |
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$this->solver = $solver; |
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} |
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public function isDiggableAndUniquelySolvableAfterDigging(Grid $grid, Location $location, int $bound): bool |
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{ |
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return $this->isDiggable($grid, $location, $bound) |
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&& $this->isUniquelySolvableAfterDigging($grid, $location); |
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} |
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private function isDiggable(Grid $grid, Location $location, int $bound): bool |
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{ |
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return !$grid->isEmpty($location) |
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&& $this->rowIsDiggable($grid, $location, $bound) |
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&& $this->columnIsDiggable($grid, $location, $bound) |
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&& $this->blockIsDiggable($grid, $location, $bound); |
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} |
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private function isUniquelySolvableAfterDigging(Grid $grid, Location $location): bool |
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{ |
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$gridCopy = clone $grid; |
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$gridCopy->empty($location); |
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$possibleValues = $gridCopy->getAllPossibilitiesFor($location); |
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if (count($possibleValues) > 1) { |
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$possibleValues = array_diff($possibleValues, [$grid->get($location)]); |
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foreach ($possibleValues as $possibleValue) { |
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$gridCopy->set($location, $possibleValue); |
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try { |
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$this->solver->solve($gridCopy); |
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} catch (UnsolvableException $exception) { |
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return false; |
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} |
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} |
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} |
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return true; |
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} |
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private function rowIsDiggable(Grid $grid, Location $location, int $bound): bool |
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{ |
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$row = $grid->getRow($location->getRow()); |
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return $this->sectionIsDiggable($row, $bound); |
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} |
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private function columnIsDiggable(Grid $grid, Location $location, int $bound): bool |
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{ |
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$column = $grid->getColumn($location->getColumn()); |
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return $this->sectionIsDiggable($column, $bound); |
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} |
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private function blockIsDiggable(Grid $grid, Location $location, int $bound): bool |
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{ |
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$block = $grid->getBlockAt($location); |
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return $this->sectionIsDiggable($block, $bound); |
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} |
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private function sectionIsDiggable(array $values, int $bound): bool |
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{ |
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return $this->numberOfNonEmptyValues($values) > $bound; |
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} |
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/** |
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* @param int[] $values |
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* |
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* @return int |
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*/ |
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private function numberOfNonEmptyValues(array $values): int |
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{ |
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return count(array_diff($values, [Grid::EMPTY_VALUE])); |
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} |
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} |
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