Citerus challenge

stripper.rb

class Stripper   
  def initialize(acronyms)
    @stripCache = {}  
    @acronyms = acronyms
  end
  
  def strip(source)
    return @stripCache[source] if @stripCache.has_key?(source)
    result = source
    @acronyms.each do |acronym|
      i = source.index(acronym)
      while !i.nil? && 0 <= i && source.length > i do 
        result = shortest(result, strip(source[0, i] + source[i + acronym.length..-1]))
        i = source.index(acronym, i + 1)
      end
    end
    @stripCache[source] = result;
    result
  end
  
  def shortest(s1, s2) 
    s1.length < s2.length ? s1 : s2;
  end
end

Stripper.new(%W[TDD DDD DI DO OO UI ANT CV IOC LOC SU VO]).strip("VOCDIITEIOCRUDOIANTOCSLOIOCVESTAIOCVOLIOCENTSU")