Function to do run-length encoding on an Array

rle.rb

class Array
  # See https://en.wikipedia.org/wiki/Run-length_encoding.
  def rle
    chunk {|e| e }.map {|e, a| [e, a.length] }
  end
end



raise "Incorrect rle function." unless [1,1,1,2,3,3].rle == [
  [1,3],
  [2,1],
  [3,2],
]