Implementation of a Burrows-Wheeler Transform, as guided by https://github.com/zetter/burrows-wheeler-transform

bwt.rb

class BWT

  def encode(string)
    chars = "#{string}$".chars
    rotations = []
    chars.length.times.
      inject(chars) do |new_chars, _|
        rotations << new_chars
        new_chars.rotate
      end
    rotations.
      sort.
      map(&:last).
      join
  end

  def decode(encoded_string)
    encoded_string.length.
      times.
      inject(encoded_string.length.times.map {|_| '' }) do |strings, _|
        strings.map.with_index do |str, idx|
          str.prepend(encoded_string[idx])
        end.sort
      end.
      detect { |string| string[-1] == '$' }[0..-2]
  end
end