Code to help analyze games of Ghost

ghost.rb

Words = File.new("./pruned-words.txt").read.split("\n")

class String
  def starts_with?(str)
    self[0..str.length - 1] == str
  end
end

# Players can never play "bones", e.g., since the game would end with "bone".
# The next two functions remove all 128,832 such extraneous words from our word list.
def prune(words)
  rejects = []
  words.each_with_index do |w, i|
    begin
      while (nw = words[i + 1]).starts_with?(w)
        rejects << nw unless w.length < 4
        i += 1
      end
    rescue
    end
  end
  words - rejects.uniq
end

def create_pruned_word_list
  words, f = File.open("./WORD.LST").read.split("\n"), File.new("./pruned-words.txt", "w")
  ("a".."z").each {|l| f.puts prune(words.select {|w| w[0..0] == l}).join("\n")}
end

def alive(root, words=Words)
  words.select {|w| w.starts_with?(root)}
end

def winner(word)
  word.length % 2 == 0 ? "h" : "c"
end

def options(root, words=Words)
  alive(root, words).collect {|w| root + w[root.length..-1][0..0]}.uniq
end

def scenario(root, words=Words)
  puts (root.length % 2 == 0 ? "h" : "c") + " to move..."
  (options(root) - [root]).each do |o|
    puts "#{root}-#{o[-1..-1].upcase}:"
    options(o).each do |op|
      alive(op, words).each do |a|
        puts "  > #{a} (#{winner(a)})"
      end
    end
  end
end

scenario("aeci")