Comparing different solutions in a variety of "functional first" languages for a poker problem
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Various solutions to the Project Euler Poker puzzle

The aim is to write various solutions to the problem below in various different functional programming lanaguages, so we can learn from each other. With that in mind, I would suggest:

  • Aim to write the solution in idomatic code for the given language
  • As we want to learn from each other, make it readable over concise, with comments where appropriate

Problem description

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.

Hand Player 1 Player 2 Winner
1 5H 5C 6S 7S KD
Pair of Fives
 2C 3S 8S 8D TD
Pair of Eights
 Player 2
2 5D 8C 9S JS AC
Highest card Ace
 2C 5C 7D 8S QH
Highest card Queen
 Player 1
3 2D 9C AS AH AC
Three Aces
 3D 6D 7D TD QD
Flush with Diamonds
 Player 2
4 4D 6S 9H QH QC
Pair of Queens
Highest card Nine
 3D 6D 7H QD QS
Pair of Queens
Highest card Seven
 Player 1
5 2H 2D 4C 4D 4S
Full House
With Three Fours
 3C 3D 3S 9S 9D
Full House
with Three Threes
 Player 1

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?