I’m playing around with elixir and solving some leetcode problems but I ran into an issue. The following code:

defmodule Solution do
  @spec climb_stairs(n :: integer) :: integer
  def climb_stairs(n) do
    climb_stairs(n, [1,0]) 
  end

  def climb_stairs(1, lis) do
    [first, second | _] = lis
    first + second
  end

  def climb_stairs(n, lis) do
    [first, second ] = lis
    climb_stairs(n-1, [first + second, second])
  end
end

always has lis be [1,0] (the result is always 1). Could someone explain what I’m doing wrong?