def max_multiplication(str)
  return unless str.is_a?(String)

  digital_combinations = str.scan(/\d+/).select { |item| item.length >= 4 }

  return if digital_combinations.empty?

  best_digital_combination = digital_combinations.map { |item| item.chars.sort { |a, b| b <=> a }.take(4) }.max
  best_digital_combination.map(&:to_i).reduce(:*)
end

def sort(array_of_numbers)
  array_of_numbers.map { |number| number.to_s(2) }.sort do |a, b|
    if a.count('1') == b.count('1')
      a.to_i(2) <=> b.to_i(2)
    else
      a.count('1') <=> b.count('1')
    end
  end.map { |number| number.to_i(2) }
end

p(max_multiplication('abc12345def'))
p(max_multiplication('a1b2c3d4e'))
p(max_multiplication('ds23fgf99fdsd54fd90'))

p(sort([3,7,8,9]))
p(sort([3,12,15,5]))