day_one.ex

# Part One
defmodule DayOnePartOne do
  def compare([number, number], acc), do: acc + number
  def compare(_, acc), do: acc
  def calculate(nums) do
    nums
    |> String.split("", trim: true)
    |> Enum.map(&String.to_integer/1)
    |> Stream.cycle
    |> Stream.take(String.length(nums) + 1)
    |> Stream.chunk_every(2, 1, :discard)
    |> Enum.reduce(0, &compare/2)
  end
end

"4443"
|> Giggles.calculate
|> IO.inspect

# Part Two

defmodule DayOnePartTwo do
  def compare({number, number}, acc), do: acc + number
  def compare(_, acc), do: acc
  def multiply(num1, num2), do: num1 * num2
  def calculate(nums) do
    split = nums
    |> String.length
    |> div(2)

    nums
    |> String.graphemes
    |> Enum.map(&String.to_integer/1)
    |> Enum.split(split)
    |> Tuple.to_list
    |> Enum.zip
    |> Enum.reduce(0, &compare/2)
    |> multiply(2)
  end
end

"1212"
|> Giggles.calculate
|> IO.inspect(label: "Result")