aoc2018/day1.exs

defmodule DayOne do
  def part_one(input) do
    String.split(input, "\n")
    |> Enum.map(&DayOne.parseNum/1)
    |> List.foldr(0, &(&1 + &2))
  end

  def part_two(input),
    do: partTwo(String.split(input, "\n") |> Enum.map(&DayOne.parseNum/1), 0, [])

  def part_two(input, acc, frequencies) do
    [head | tail] = input
    freq = head + acc
    # IO.puts("Got frequency #{freq}")
    if Enum.member?(frequencies, freq),
      do: freq,
      else: partTwo(tail ++ [head], freq, [freq | frequencies])
  end

  def parse_num("+" <> num) do
    {intVal, ""} = Integer.parse(num)
    intVal
  end

  def parse_num("-" <> num) do
    {intVal, ""} = Integer.parse(num)
    0 - intVal
  end

  def parse_num(num) do
    IO.puts(num)
    0
  end
end