From: Brian Krahmer <brian@...>
Date: 2007-04-26T06:42:52+09:00
Subject: [QUIZ][SOLUTION] Morse Code (#121)

Here is my solution to the morse code problem.  The meat of is only 
about 10 lines, and I think it's pretty readable, so hopefully it will 
be viewed as a good solution.  I used the dictionary installed on my 
ubuntu system to display a * after words found in it.  BTW, this is my 
first submission.

brian

require 'singleton'

class Word
  LETTERS = [ ['.-', 'A'], ['-.', 'N'], ['-...', 'B'], ['---', 'O'],
    ['-.-.', 'C'], ['.--.', 'P'], ['-..', 'D'], ['--.-', 'Q'], ['.', 'E'],
    ['.-.', 'R'], ['..-.', 'F'], ['...', 'S'], ['--.', 'G'], ['-', 'T'],
    ['....', 'H'], ['..-', 'U'], ['..', 'I'], ['...-', 'V'], ['.---', 'J'],
    ['.--', 'W'], ['-.-', 'K'], ['-..-', 'X'], ['.-..', 'L'], ['-.--', 'Y'],
    ['--', 'M'], ['--..', 'Z'] ]

  def initialize(word)
    @morse = word
  end
 
  def parse
    check_match(0, [], 0)
  end
 
  def check_match(word_offset, found_letters, found_letters_length)
    if found_letters_length == @morse.size
      word = found_letters.join('') 
      print word
      print ' *' if Dictionary.instance.has_word?(word)
      puts
      return
    end
    0.upto(LETTERS.size-1) do |index|
      morse_letter = LETTERS[index][0]
      next if word_offset + morse_letter.size > @morse.size
      if @morse[word_offset..(word_offset + morse_letter.size - 1)] == 
morse_letter
        check_match(word_offset + morse_letter.size, 
found_letters.clone.push(LETTERS[index][1]),
          found_letters_length + morse_letter.size)
      end
    end
  end

end

class Dictionary
  include Singleton

  def load
    @entries = {}
    File.open('/usr/share/dict/words') do |file|
      file.each_line do |line|
        @entries[line.chomp.upcase] = 1
      end
    end
  end
 
  def has_word?(word)
    @entries[word]
  end
 
end

Dictionary.instance.load

until $stdin.eof?
  Word.new($stdin.gets.chomp).parse
end