Re-arranging a 1d list in Ruby

Question

I'm trying to simulate a deck of cards being cut. So I prompt the player to pick a number between 1 and 32(the number of cards in this deck). That is stored in the $cut_the_deck_number variable.

Then I need to somehow move the cards (from that number to the end of the deck), to the front of the deck.

This code somewhat works, however not good, b.c it creates a 2D array, when I just need a list.

I need $deck to be

$deck = ["2 of diamonds", "5 of clubs", etc]

instead of

$deck = [["2 of diamonds, "5 of clubs"], ["8 of spades", etc, etc]]

I know there is some other method, but it wouldn't work because I'm using RUBY 1.8.7

def cuttingthedeck
  bottomcut = $deck.pop($cut_the_deck_number)
  topcut = $deck.pop($deck.length)
  $deck.push(bottomcut)
  $deck.push(topcut)
end

Answer 1

Just add the two halves back together:

$deck = bottomcut + topcut

In Ruby, adding arrays is equivalent to concatenating their elements:

irb(main):001:0> [1, 2, 3] + [3, 4, 5]
=> [1, 2, 3, 3, 4, 5]

Answer 2

You could flatten your array: $deck.flatten!. This is an alternative:

deck = ["a", "b", "c", "d", "e"]
cut = 2
deck += deck.slice!(0, cut)
p deck #=> ["c", "d", "e", "a", "b"]

Answer 3

Personally, I'd use classes to represent the deck and the cards…

Cards might be:

class Card
  attr_reader :suit, :value

  def initialize(suit, value)
    @suit, @value = suit, value
  end

  def to_s
    value = case @value
    when 1
      :A
    when 11
      :J
    when 12
      :Q
    when 13
      :K
    else
      @value
    end

    "#{value}#{suit}"
  end

  alias_method :inspect, :to_s
end

And Deck could look like:

class Deck
  attr_reader :cards

  def initialize
    @cards = []

    [:S, :H, :D, :C].each do |suit|
      ([1] + (7..13).to_a).each do |value|
        @cards << Card.new(suit, value)
      end
    end
  end

  def shuffle!
    @cards.shuffle!
    self
  end

  def cut!(cut_at = nil)
    cut_at ||= rand(1..(@cards.size - 1))
    @cards += @cards.slice!(0, cut_at)
    self
  end
end

You could then call:

require 'pp'
pp Deck.new.shuffle!.cut!