Question

as I am learning the Ruby language, I am getting closer to actual programming. I was thinking of creating a simple card game. My question isn’t Ruby oriented, but I do know want to learn how to solve this problem with a genuine OOP approach. In my card game, I want to have four players, using a standard deck with 52 cards, no jokers/wildcards. In the game, I won’t use the ace as a dual card, it is always the highest card.

So, the programming problems I wonder about are the following:

1. How can I sort/randomize the deck of cards? There are four types, each having 13 values. Eventually there can be only unique values, so picking random values could generate duplicates.

2. How can I implement a simple AI? As there are tons of card games, someone would have figured this part out already, so references would be great.

I am a true Ruby nuby, and my goal here is to learn to solve problems, so pseudo code would be great, just to understand how to solve the problem programmatically. I apologize for my grammar and writing style if it’s unclear, for it is not my native language.

Also, pointers to sites where such challenges are explained would be a great resource!

Thank you for your comments, answers and feedback!

Answer 1

Something to get you started

You can ensure unique cards very easily by using numbers from 0 to 51.

The Array#shuffle method is based off the Knuth-Fisher-Yates shuffle algorithm. http://en.wikipedia.org/wiki/Fisher–Yates_shuffle

class Card
  RANKS = %w(2 3 4 5 6 7 8 9 10 J Q K A)
  SUITS = %w(Spade Heart Club Diamond)

  attr_accessor :rank, :suit

  def initialize(id)
    self.rank = RANKS[id % 13]
    self.suit = SUITS[id % 4]
  end
end

class Deck
  attr_accessor :cards
  def initialize
    # shuffle array and init each Card
    self.cards = (0..51).to_a.shuffle.collect { |id| Card.new(id) }
  end
end

# people with Ruby 1.9 (or 1.8.7 with backports) can safely ignore this duck punch
class Array
  # knuth-fisher-yates shuffle algorithm
  def shuffle!
    n = length
    for i in 0...n
      r = rand(n-i)+i
      self[r], self[i] = self[i], self[r]
    end
    self
  end
  def shuffle
    dup.shuffle!
  end
end

test

d = Deck.new
d.cards.each do |card|
  puts "#{card.rank} #{card.suit}"
end

output

6 Spade
5 Heart
2 Heart
8 Heart
8 Diamond
7 Club
J Diamond
4 Club
K Spade
5 Diamond
J Heart
8 Spade
10 Club
4 Diamond
9 Heart
7 Diamond
3 Diamond
K Diamond
7 Spade
Q Diamond
9 Diamond
6 Heart
A Heart
9 Club
A Spade
5 Club
J Club
Q Spade
2 Club
2 Spade
Q Heart
A Diamond
10 Spade
10 Diamond
Q Club
3 Club
A Club
K Club
6 Club
10 Heart
2 Diamond
3 Spade
K Heart
5 Spade
9 Spade
7 Heart
4 Spade
J Spade
3 Heart
4 Heart
8 Club
6 Diamond