{"id":"ood-deck-of-cards","title":"Design a deck of cards","sections":[{"id":"constraints-and-assumptions","title":"Constraints and assumptions","html":"

Constraints and assumptions

\n","headings":[]},{"id":"solution","title":"Solution","html":"

Solution

\n
from abc import ABCMeta, abstractmethod\nfrom enum import Enum\nimport sys\n\n\nclass Suit(Enum):\n\n    HEART = 0\n    DIAMOND = 1\n    CLUBS = 2\n    SPADE = 3\n\n\nclass Card(metaclass=ABCMeta):\n\n    def __init__(self, value, suit):\n        self.value = value\n        self.suit = suit\n        self.is_available = True\n\n    @property\n    @abstractmethod\n    def value(self):\n        pass\n\n    @value.setter\n    @abstractmethod\n    def value(self, other):\n        pass\n\n\nclass BlackJackCard(Card):\n\n    def __init__(self, value, suit):\n        super(BlackJackCard, self).__init__(value, suit)\n\n    def is_ace(self):\n        return self._value == 1\n\n    def is_face_card(self):\n        \"\"\"Jack = 11, Queen = 12, King = 13\"\"\"\n        return 10 < self._value <= 13\n\n    @property\n    def value(self):\n        if self.is_ace() == 1:\n            return 1\n        elif self.is_face_card():\n            return 10\n        else:\n            return self._value\n\n    @value.setter\n    def value(self, new_value):\n        if 1 <= new_value <= 13:\n            self._value = new_value\n        else:\n            raise ValueError('Invalid card value: {}'.format(new_value))\n\n\nclass Hand(object):\n\n    def __init__(self, cards):\n        self.cards = cards\n\n    def add_card(self, card):\n        self.cards.append(card)\n\n    def score(self):\n        total_value = 0\n        for card in self.cards:\n            total_value += card.value\n        return total_value\n\n\nclass BlackJackHand(Hand):\n\n    BLACKJACK = 21\n\n    def __init__(self, cards):\n        super(BlackJackHand, self).__init__(cards)\n\n    def score(self):\n        min_over = sys.MAXSIZE\n        max_under = -sys.MAXSIZE\n        for score in self.possible_scores():\n            if self.BLACKJACK < score < min_over:\n                min_over = score\n            elif max_under < score <= self.BLACKJACK:\n                max_under = score\n        return max_under if max_under != -sys.MAXSIZE else min_over\n\n    def possible_scores(self):\n        \"\"\"Return a list of possible scores, taking Aces into account.\"\"\"\n        # ...\n\n\nclass Deck(object):\n\n    def __init__(self, cards):\n        self.cards = cards\n        self.deal_index = 0\n\n    def remaining_cards(self):\n        return len(self.cards) - deal_index\n\n    def deal_card():\n        try:\n            card = self.cards[self.deal_index]\n            card.is_available = False\n            self.deal_index += 1\n        except IndexError:\n            return None\n        return card\n\n    def shuffle(self):  # ...
","headings":[]}],"sourceFiles":[{"name":"deck_of_cards.py","url":"https://github.com/donnemartin/system-design-primer/blob/master/solutions/object_oriented_design/deck_of_cards/deck_of_cards.py","html":"
from abc import ABCMeta, abstractmethod\nfrom enum import Enum\nimport sys\n\n\nclass Suit(Enum):\n\n    HEART = 0\n    DIAMOND = 1\n    CLUBS = 2\n    SPADE = 3\n\n\nclass Card(metaclass=ABCMeta):\n\n    def __init__(self, value, suit):\n        self.value = value\n        self.suit = suit\n        self.is_available = True\n\n    @property\n    @abstractmethod\n    def value(self):\n        pass\n\n    @value.setter\n    @abstractmethod\n    def value(self, other):\n        pass\n\n\nclass BlackJackCard(Card):\n\n    def __init__(self, value, suit):\n        super(BlackJackCard, self).__init__(value, suit)\n\n    def is_ace(self):\n        return True if self._value == 1 else False\n\n    def is_face_card(self):\n        \"\"\"Jack = 11, Queen = 12, King = 13\"\"\"\n        return True if 10 < self._value <= 13 else False\n\n    @property\n    def value(self):\n        if self.is_ace() == 1:\n            return 1\n        elif self.is_face_card():\n            return 10\n        else:\n            return self._value\n\n    @value.setter\n    def value(self, new_value):\n        if 1 <= new_value <= 13:\n            self._value = new_value\n        else:\n            raise ValueError('Invalid card value: {}'.format(new_value))\n\n\nclass Hand(object):\n\n    def __init__(self, cards):\n        self.cards = cards\n\n    def add_card(self, card):\n        self.cards.append(card)\n\n    def score(self):\n        total_value = 0\n        for card in self.cards:\n            total_value += card.value\n        return total_value\n\n\nclass BlackJackHand(Hand):\n\n    BLACKJACK = 21\n\n    def __init__(self, cards):\n        super(BlackJackHand, self).__init__(cards)\n\n    def score(self):\n        min_over = sys.MAXSIZE\n        max_under = -sys.MAXSIZE\n        for score in self.possible_scores():\n            if self.BLACKJACK < score < min_over:\n                min_over = score\n            elif max_under < score <= self.BLACKJACK:\n                max_under = score\n        return max_under if max_under != -sys.MAXSIZE else min_over\n\n    def possible_scores(self):\n        \"\"\"Return a list of possible scores, taking Aces into account.\"\"\"\n        pass\n\n\nclass Deck(object):\n\n    def __init__(self, cards):\n        self.cards = cards\n        self.deal_index = 0\n\n    def remaining_cards(self):\n        return len(self.cards) - self.deal_index\n\n    def deal_card(self):\n        try:\n            card = self.cards[self.deal_index]\n            card.is_available = False\n            self.deal_index += 1\n        except IndexError:\n            return None\n        return card\n\n    def shuffle(self):\n        pass
"}]}