module SimilarStrings

# File lib/similar_strings.rb, line 5
def self.score(str1, str2)
  return 0 if str1.blank? || str2.blank?
  str1.downcase! if !str1.blank?
  pairs1 = (0..str1.length-2).collect {|i| str1[i,2]}.reject {
    |pair| pair.include? " "}
  str2.downcase! if !str2.blank?
  pairs2 = (0..str2.length-2).collect {|i| str2[i,2]}.reject {
    |pair| pair.include? " "}
  union = pairs1.size + pairs2.size 
  intersection = 0 
  pairs1.each do |p1| 
    0.upto(pairs2.size-1) do |i| 
      if p1 == pairs2[i] 
        intersection += 1 
        pairs2.slice!(i) 
        break 
      end 
    end 
  end 
  (2.0 * intersection) / union
end