Project Euler Problem 054

# 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)
```