gistfile1.rb

# Solves Stanford's SAAS anagram question
# http://spark-university.s3.amazonaws.com/berkeley-saas/homework/hw1.pdf
# Question 3

def combine_anagrams(words)

  # Set up a hash to hold the groups:
  #   Keys will be the sorted anagram string
  #   Values will be the array of anagrams for that string
  # Hash works well here because it's a fast lookup on
  # the key, even when the words array gets really long.
  groups = {}

  # Iterate over the words list
  words.each do |word|
    # Find the anagram key, which is the sorted lowercase letters
    # "ElliottWood" becomes "deillooottw"
    chars = word.downcase.chars.sort.join

    # Key into the groups hash for that anagram key
    # Set it to an empty array if it doesn't exist,
    # then append the current word to that array.
    groups[chars] ||= []
    groups[chars] << word
  end

  # The Hash#values fetches the arrays without
  # the keys, which is the desired return format.
  groups.values

end