dictionary_solution.rb

#   Solution to the following:
#   Given a dictionary, output all word pairs where both words share all their letters except the last two, which are distinct and reversed.
# 
# Notes:
#   - Use a reasonable dictionary of your choice
#   - Potential word pairs are: "ear, era" ; "revies, revise" ; "burglaries, burglarise"
#   - "shear, era" is not a valid pair because "she" != "e"
#   - "bell, bell" is not a valid pair because the last two letters are not distinct
#   - This will be benchmarked
#   - Work on this problem in C, C++, Java, Perl, PHP, Python or a similar language.
#   - Don't e-mail to ask for clarifications on this question.
#     Make reasonable assumptions and justify them in a README if you feel the need

time = Time.now.to_f
dictionary, results = [], []

# copy the contents of the file to our dictionary
File.open("dictionary.txt") do |file|
  while line = file.gets
    dictionary << line.gsub(/(\n)/, '')
  end
end

dictionary.uniq!

# compile our word pairs from the dictionary
while curr = dictionary.delete_at(0) do
  next unless curr.size >= 2 && curr[-1] != curr[-2]
  search = curr[0...-2] + curr[-2..-1].reverse
  results << (curr + ', ' + search) if dictionary.delete(search)
end

time = Time.now.to_f - time
puts results
puts "Found #{results.size} pairs in #{time.to_s} seconds"