gistfile1.rb

def compress(input)
  previous_char = nil
  current_count = 0
  output = ""

  input.each_char do |c|
    if c == previous_char || previous_char == nil
      current_count += 1
    elsif previous_char != nil
       output << "#{current_count}#{previous_char}"
       current_count = 1
    end

    previous_char = c
  end

  output << "#{current_count}#{previous_char}"

  output
end

input = "AAABBCCCDDAA"
expected = "3A2B3C2D2A"

if compress(input) != expected
  p compress(input)
  p expected
  fail
end