aoc 1.exs

1.exs

defmodule One do
  def split(str) do
    [String.slice(str, 0..0), String.to_integer(String.slice(str, 1..-1))]
  end

  def value("+", n), do: n
  def value("-", n), do: -n

  def split_value(str) do
    apply(One, :value, split(str))
  end
end

defmodule OneTwo do
  def next([n | rest], freq, freqs) do
    nf = freq + One.split_value(n)
    find(rest ++ [n], nf, [nf | freqs])
  end

  def find(list, freq, []) do
    next(list, freq, [])
  end

  def find(list, freq, freqs) do
    [_ | old_freqs] = freqs

    cond do
      freq in old_freqs -> freq
      true -> next(list, freq, freqs)
    end
  end
end

{:ok, content} = File.read("1.txt")
lines = String.split(content)

# Answer 1
IO.puts(Enum.reduce(lines, 0, fn x, acc -> One.split_value(x) + acc end))

# Answer 2
IO.puts(OneTwo.find(lines, 0, []))