def bubble_sort(array)
  @swap_needed = false
  array.each_with_index do |val, idx|
    a = val
    b = array[idx + 1]

    if !b.nil? && a > b
      @swap_needed = true
      array[idx] = b
      array[idx + 1] = a
    end
  end
  @swap_needed ? bubble_sort(array) : array
end