day3

Section

Mix.install([:kino])

input = Kino.Input.textarea("input file: ")

input = Kino.Input.read(input)

defmodule Recursion do
  def rec([head | tail], x, count, [right, 1]) do
    let = String.at(head, x)
    bool = if let == "#", do: 1, else: 0
    modulo_x = rem(x + right, String.length(head))
    rec(tail, modulo_x, count + bool, [right, 1])
  end

  def rec([head | tail], x, count, [right, 2]) do
    let = String.at(head, x)
    bool = if let == "#", do: 1, else: 0
    modulo_x = rem(x + right, String.length(head))
    tail_tail = List.delete_at(tail, 0)
    rec(tail_tail, modulo_x, count + bool, [right, 2])
  end

  def rec([], _, count, _) do
    count
  end
end

map = String.split(input)

part1 =
  map
  |> Recursion.rec(0, 0, [3, 1])
  |> IO.puts()

directions = [[1, 1], [3, 1], [5, 1], [7, 1], [1, 2]]
x = for dir <- directions, do: Recursion.rec(map, 0, 0, dir)

part2 =
  x
  |> Enum.reduce(&amp;(&amp;1 * &amp;2))
  |> IO.puts()