ex0105.rb

def compress_before_seeing_avdis_answer(str)
  result = str.chars.chunk(&:to_s).map { |char, chars| "#{char}#{chars.length}" }.join
  return str if result.length > str.length
  result
end

def compress(str)
  [
    str
    str.chars.chunk(&:to_s).map { |char, chars| "#{char}#{chars.length}" }.join,
  ].min_by(&:length)
end

def decompress(str)
  #double split and double empty seems like a huge smell. Something is a miss here.
  [
    str.split(/([a-z][0-9]+)/)
       .reject(&:empty?)
       .map do |num|
          alpha_num = num.split(/([a-z]|[0-9]+)/).reject(&:empty?)
          alpha_num.first * alpha_num.last.to_i
       end.join,
    str
  ].max_by(&:length)
end

describe 'compress / decompress' do
  cases = [
    ['a', 'a'],
    ['aa', 'aa'],
    ['aaa', 'a3'],
    ['abc', 'abc'],
    ['aaaaaaaaaaac', 'a11c1'],
    ['aabcccccaa', 'a2b1c5a2'],
  ]
  cases.each do |start, finish|
    it "compresses #{start} into #{finish}" do
      expect(compress(start)).to eq(finish)
    end
  end
  cases.each do |finish, start|
    it "decompresses #{start} into #{finish}" do
      expect(decompress(start)).to eq(finish)
    end
  end
end