Statement
In the card game poker, a hand consists of five cards and are ranked, from lowest to highest, in the following way:
- High Card: Highest value card.
- One Pair: Two cards of the same value.
- Two Pairs: Two different pairs.
- Three of a Kind: Three cards of the same value.
- Straight: All cards are consecutive values.
- Flush: All cards of the same suit.
- Full House: Three of a kind and a pair.
- Four of a Kind: Four cards of the same value.
- Straight Flush: All cards are consecutive values of same suit.
- Royal Flush: Ten, Jack, Queen, King, Ace, in same suit.
The cards are valued in the order:
2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King, Ace.
If two players have the same ranked hands then the rank made up of the highest value wins; for example, a pair of eights beats a pair of fives (see example 1 below). But if two ranks tie, for example, both players have a pair of queens, then highest cards in each hand are compared (see example 4 below); if the highest cards tie then the next highest cards are compared, and so on.
The file, poker.txt, contains one-thousand random hands dealt to two players. Each line of the file contains ten cards (separated by a single space): the first five are Player 1's cards and the last five are Player 2's cards. You can assume that all hands are valid (no invalid characters or repeated cards), each player's hand is in no specific order, and in each hand there is a clear winner.
How many hands does Player 1 win?
Solution
To solve this particular problem I use an object-oriented approach. Each type of poker hand is a subclass of the PokerHand class, then I use double dispatching to determine who the winner is.
class PokerHand: def __init__(self, cards): self.cards = cards @classmethod def create_hand(cls, cards): new_cards = [] numbers = {} for n, c in cards: if n == 'T': n = 10 elif n == 'J': n = 11 elif n == 'Q': n = 12 elif n == 'K': n = 13 elif n == 'A': n = 14 else: n = int(n) new_cards.append((n,c)) numbers[n] = numbers.get(n, 0) + 1 is_flush = len(set([c for n,c in new_cards])) == 1 is_straight = len(numbers) == 5 and (max(numbers) - min(numbers) == 4 or set([2, 3, 4, 5, 14]) == set(numbers.keys())) if is_flush and is_straight: if set([2, 3, 4, 5, 14]) == set(numbers.keys()): numbers[1] = 1 del numbers[14] return StraightFlush(numbers) if is_flush: return Flush(numbers) if is_straight: if set([2, 3, 4, 5, 14]) == set(numbers.keys()): numbers[1] = 1 del numbers[14] return Straight(numbers) card_counts = sorted(numbers.values()) if card_counts == [1,4]: return Poker(numbers) if card_counts == [2,3]: return FullHouse(numbers) if card_counts == [1,1,3]: return ThreeOfAKind(numbers) if card_counts == [1,2,2]: return DoublePair(numbers) if card_counts == [1,1,1,2]: return Pair(numbers) return HighCard(numbers) class StraigthFlush(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsStraightFlush(self) def beatsStraightFlush(self, poker_hand): return max(self.cards) > max(poker_hand.cards) def beatsPoker(self, poker_hand): return True beatsFullHouse = beatsFlush = beatsStraight = beatsThreeOfAKind = beatsDoublePair = beatsPair = beatsHighCard = beatsPoker class Poker(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsPoker(self) def beatsStraightFlush(self, poker_hand): return False def beatsPoker(self, poker_hand): poker_card_me = next(filter(lambda k: self.cards[k] == 4, self.cards)) poker_card_other = next(filter(lambda k: poker_hand.cards[k] == 4, poker_hand.cards)) if poker_card_me > poker_card_other: return True else: return False def beatsFullHouse(self, poker_hand): return True beatsFlush = beatsStraight = beatsThreeOfAKind = beatsDoublePair = beatsPair = beatsHighCard = beatsFullHouse class FullHouse(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsFullHouse(self) def beatsStraightFlush(self, poker_hand): return False beatsPoker = beatsStraightFlush def beatsFullHouse(self, poker_hand): full_card_me = next(filter(lambda k: self.cards[k] == 3, self.cards)) full_card_other = next(filter(lambda k: poker_hand.cards[k] == 3, poker_hand.cards)) return full_card_me > full_card_other def beatsFlush(self, poker_hand): return True beatsStraight = beatsThreeOfAKind = beatsDoublePair = beatsPair = beatsHighCard = beatsFlush class Flush(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsFlush(self) def beatsStraightFlush(self, poker_hand): return False beatsFullHouse = beatsPoker = beatsStraightFlush def beatsFlush(self, poker_hand): my_cards = sorted(self.cards, key=lambda x: -x) other_cards = sorted(poker_hand.cards, key=lambda x: -x) return my_cards > other_cards def beatsStraight(self, poker_hand): return True beatsThreeOfAKind = beatsDoublePair = beatsPair = beatsHighCard = beatsStraight class Straight(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsStraight(self) def beatsStraightFlush(self, poker_hand): return False beatsFlush = beatsFullHouse = beatsPoker = beatsStraightFlush def beatsStraight(self, poker_hand): return max(self.cards) > max(poker_hand.cards) def beatsThreeOfAKind(self, poker_hand): return True beatsDoublePair = beatsPair = beatsHighCard = beatsThreeOfAKind class ThreeOfAKind(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsThreeOfAKind(self) def beatsStraightFlush(self, poker_hand): return False beatsStraight = beatsFlush = beatsFullHouse = beatsPoker = beatsStraightFlush def beatsThreeOfAKind(self, poker_hand): three_card_me = next(filter(lambda k: self.cards[k] == 3, self.cards)) three_card_other = next(filter(lambda k: poker_hand.cards[k] == 3, poker_hand.cards)) return three_card_me > three_card_other def beatsDoublePair(self, poker_hand): return True beatsPair = beatsHighCard = beatsDoublePair class DoublePair(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsDoublePair(self) def beatsStraightFlush(self, poker_hand): return False beatsThreeOfAKind = beatsStraight = beatsFlush = beatsFullHouse = beatsPoker = beatsStraightFlush def beatsDoublePair(self, poker_hand): two_cards_me = sorted(filter(lambda k: self.cards[k] == 2, self.cards), key=lambda x: -x) two_cards_other = sorted(filter(lambda k: poker_hand.cards[k] == 2, poker_hand.cards), key=lambda x: -x) if two_cards_me > two_cards_other: return True elif two_cards_me < two_cards_other: return False else: one_card_me = next(filter(lambda k: self.cards[k] == 1, self.cards)) one_card_other = next(filter(lambda k: poker_hand.cards[k] == 1, poker_hand.cards)) return one_card_me > one_card_other def beatsPair(self, poker_hand): return True beatsHighCard = beatsPair class Pair(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsPair(self) def beatsStraightFlush(self, poker_hand): return False beatsDoublePair = beatsThreeOfAKind = beatsStraight = beatsFlush = beatsFullHouse = beatsPoker = beatsStraightFlush def beatsPair(self, poker_hand): two_card_me = next(filter(lambda k: self.cards[k] == 2, self.cards)) two_card_other = next(filter(lambda k: poker_hand.cards[k] == 2, poker_hand.cards)) if two_card_me > two_card_other: return True elif two_card_me < two_card_other: return False else: one_cards_me = sorted(filter(lambda k: self.cards[k] == 1, self.cards), key=lambda x: -x) one_cards_other = sorted(filter(lambda k: poker_hand.cards[k] == 1, poker_hand.cards), key=lambda x: -x) return one_cards_me > one_cards_other def beatsHighCard(self, poker_hand): return True class HighCard(PokerHand): def beats(self, poker_hand): return not poker_hand.beatsHighCard(self) def beatsStraightFlush(self, poker_hand): return False beatsPair = beatsDoublePair = beatsThreeOfAKind = beatsStraight = beatsFlush = beatsFullHouse = beatsPoker = beatsStraightFlush def beatsHighCard(self, poker_hand): return sorted(self.cards, key=lambda x: -x) > sorted(poker_hand.cards, key=lambda x: -x) if __name__ == '__main__': result = sum(1 for line in open('poker.txt') if PokerHand.create_hand(line.strip().split(' ')[:5]).beats(PokerHand.create_hand(line.strip().split(' ')[5:]))) print("The result is:", result)
The Python file is available for download here.