rle.rb

def rle(str)
  current = {}
  str.chars.each_with_object([]) do |char, arr|
    if current.empty?
      current = {"#{char}": 1}
    elsif current.keys.first == char.to_sym
      current[:"#{char}"] += 1
    else
      arr << current
      current = {"#{char}": 1}
    end
  end << current
end

def rld(arr)
  arr.each_with_object("") do |pair, str|
    str << pair.keys.first.to_s * pair.values.first
  end
end