Full Decks Solution (PHP)

FullDeck.php

<?php

declare(strict_types=1);

final class FullDeck
{
    public function cards(): array
    {
        static $cards;

        if (null === $cards) {
            $ranks = ['2', '3', '4', '5', '6', '7', '8', '9', 'T', 'J', 'Q', 'K', 'A'];
            $suits = ['S', 'C', 'H', 'D'];

            $cards = [];

            foreach ($ranks as $rank) {
                foreach ($suits as $suit) {
                    $cards[] = $rank . $suit;
                }
            }
        }

        return $cards;
    }
}

FullDecks.php

<?php

declare(strict_types=1);

final class FullDecks
{
    /**
     * @var FullDeck
     */
    private $fullDeck;

    public function __construct(FullDeck $fullDeck)
    {
        $this->fullDeck = $fullDeck;
    }

    /**
     * @param string[] $cards
     *
     * @return int
     */
    public function __invoke(array $cards): int
    {
        $count = 0;

        while (\count($cards)) {
            foreach ($this->fullDeck->cards() as $card) {
                $key = \array_search(
                    $card,
                    $cards,
                    true
                );

                if (false === $key) {
                    return $count;
                }

                unset($cards[$key]);
            }

            ++$count;
        }

        return $count;
    }
}