From: Christian Neukirchen <chneukirchen@...>
Date: 2007-04-24T21:12:40+09:00
Subject: Re: [QUIZ] Morse Code (#121)

Ruby Quiz <james@grayproductions.net> writes:

> This week's quiz is to write program that displays all possible translations for
> ambiguous words provided in code.
>
> Your program will be passed a word of Morse code on STDIN.  Your program should
> print all possible translations of the code to STDOUT, one translation per line.
> Your code should print gibberish translations in case they have some meaning for
> the reader, but indicating which translations are in the dictionary could be a
> nice added feature.

This is my solution with the Morse code passed as argument; you can
enable a directory by passing -d.

It uses simple recursion.

#!ruby -s

$morse = Hash[*%w{
  A .- B -...  C -.-.  D -..  E .  F ..-.  G --.  H ....  I ..  J .---
  K -.- L .-..  M -- N -.  O --- P .--.  Q --.- R .-.  S ...  T - U ..-
  V ...- W .-- X -..- Y -.-- Z --..
}].invert

if $d
  words = {}
  File.readlines("/usr/share/dict/words").each { |word|
    words[word.downcase.chomp] = true
  }
end

def allmorse(s, t="", &b)
  if s.empty?
    yield t
  else
    1.upto(s.size) { |n|
      $morse[s[0,n]] && allmorse(s[n..-1], t+$morse[s[0,n]], &b)
    }
  end
end

allmorse (ARGV[0] || ".-...--...-.--").delete("^.-") do |word|
  puts word  if !$d || words.include?(word.downcase)
end


__END__


Example:

$ ruby quiz121.rb
ETEEETTEEETETT
ETEEETTEEETEM
ETEEETTEEETAT
ETEEETTEEETW
ETEEETTEEENTT
:   :   :   :
LPUW
LPFTT
LPFM

$ ruby quiz121.rb -d
RUBY

$ ruby quiz121.rb -d ...././.-../.-../---
HELLO

-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org