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<?php declare(strict_types=1);
namespace Stratadox\PuzzleSolver\Puzzle\WolfGoatCabbage;
use Stratadox\PuzzleSolver\Move;
use Stratadox\PuzzleSolver\Puzzle;
use Stratadox\PuzzleSolver\Moves;
use function assert;
final class RiverCrossingPuzzle implements Puzzle
{
/** @var Farmer */
private $farmer;
/** @var Moves */
private $crossings;
private function __construct(Farmer $farmer, Moves $crossings)
$this->farmer = $farmer;
$this->crossings = $crossings;
}
public static function begin(): Puzzle
return new self(Farmer::withWolfGoatAndCabbage(), Moves::none());
public function isSolved(): bool
return $this->farmer->hasMovedAllPurchasesAlong();
public function movesSoFar(): Moves
return $this->crossings;
public function representation(): string
return (string) $this->farmer;
public function possibleMoves(): Moves
return $this->farmer->possibleCrossings();
public function afterMaking(Move ...$moves): Puzzle
$new = clone $this;
foreach ($moves as $move) {
assert($move instanceof Crossing);
$new->farmer = $new->farmer->after($move);
$new->crossings = $new->crossings->add(...$moves);
return $new;
Stratadox /
PuzzleSolver
