class Fixnum
  # fibonacci instance method using loops instead of recursion
  # This variation of the fibonacci method uses loops in order to minimize memory usage
  def fibonacci
    array = [0,1]

    (2..self).each do
      #can be replaced with "2.upto(self) do" as well as "(self-1).times do"
      temp = array[0] + array[1]

      array[0] = array[1]
      array[1] = temp
    end

    array[1]
  end
end


# A bug I had while writing this method: I set the variable temp outside of the loop placing it outside the scope of the loop.
# This meant that the temp variable would never change.
# It's the equivalent of having the following code:
# class Fixnum
#   def fibonacci
#     array = [0,1]
#     temp = array[0] + array[1]
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#     array[0] = array[1]
#     array[1] = temp
#
# and so on
# temp NEVER changes. The result is that array goes from [0,1] to [1,1] and then to [1,1] over and over again.
# You take the value 1 from array[1] and place it in array[0] which is already 1 and then place temp which is 1 into array[1] which is already 1.
# Nothing changes after the first iteration.