Calculate All Moves For A Word in Letterpress Board

gistfile1.rb

# requires a board_tiles method that returns an array of objects that respond to the letter method

def board_tiles_by_letter
  by_letter = {}
  ('A'..'Z').each { |letter| by_letter[letter] = [] }
  board_tiles.each { |board_tile| by_letter[board_tile.letter] << board_tile }
  by_letter
end
  
def every_play(word)
  word_letters = word.chars.to_a
  with_duplicates = board_tiles_by_letter[word_letters.shift].product(*word_letters.map { |letter| board_tiles_by_letter[letter] })
  with_duplicates.select { |play| play.uniq.count == play.count }
end