Resolve alphabet position encoded puzzle.

alphabet_position.rb

ALPHABET = ('a'..'z').to_a
code = '2114111925'

class WordTree
  attr_accessor :l, :r, :my_letter, :string
  def initialize(my_letter, string)
    @string = string
    @my_letter = my_letter
    try_init_childs
  end

  def try_init_childs
    @l = WordTree.new(@string[0..0].to_i, @string[1..-1]) if @string.size > 0
    @r = WordTree.new(@string[0..1].to_i, @string[2..-1]) if @string.size > 1 && @string[0..1].to_i <= (ALPHABET.size+1)
  end
end

def walk_tree(tree, word=[])
  word = word+[tree.my_letter] if tree.my_letter
  print_word word if tree.string.size == 0 #Reached the end of a chain (no more letters left)
  walk_tree(tree.l, word) if tree.l
  walk_tree(tree.r, word) if tree.r
end

def print_word(arr)
  puts arr.map{|x| ALPHABET[x-1]}.join('')
end

x=WordTree.new(nil, code)
walk_tree(x)