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<?php declare(strict_types=1); |
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namespace Stratadox\PuzzleSolver\Puzzle\NQueens; |
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use Stratadox\PuzzleSolver\Moves; |
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use function array_slice; |
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use function count; |
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use function end; |
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use function implode; |
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use function range; |
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use function str_repeat; |
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use const PHP_EOL; |
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final class Board |
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{ |
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/** @var int */ |
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private $size; |
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private function __construct(int $size) |
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{ |
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$this->size = $size; |
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} |
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public static function ofSize(int $n): self |
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{ |
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return new self($n); |
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} |
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public function isSolvedWith(QueenPlacement ...$queens): bool |
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{ |
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return count($queens) === $this->size; |
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} |
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public function possibleMovesAfter(QueenPlacement ...$queens): Moves |
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{ |
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$row = empty($queens) ? 0 : (end($queens)->row() + 1); |
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$moves = []; |
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foreach (range(0, $this->size - 1) as $column) { |
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if (!$this->isBlocked($row, $column, ...$queens)) { |
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$moves[] = new QueenPlacement($row, $column); |
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} |
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} |
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return new Moves(...$moves); |
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} |
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private function isBlocked( |
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int $row, |
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int $column, |
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QueenPlacement ...$queens |
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): bool { |
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foreach ($queens as $queen) { |
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if ( |
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$queen->column() === $column || |
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$queen->row() === $row || |
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abs($queen->row() - $row) === abs($queen->column() - $column) |
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) { |
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return true; |
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} |
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} |
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return false; |
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} |
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public function __toString(): string |
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{ |
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$board = ' ' . implode(' ', array_slice(range('a', 'z'), 0, $this->size)) . PHP_EOL; |
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foreach (range($this->size, 0, -1) as $i) { |
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$board .= $i . ' ' . str_repeat(' ', $this->size) . PHP_EOL; |
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} |
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return $board; |
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} |
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} |
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Stratadox /
PuzzleSolver
