Day 3

Mix.install([
  {:kino, "~> 0.11.0"}
])

Inputs

input_box = Kino.Input.textarea("input")

input = Kino.Input.read(input_box)

Part 1

Regex.scan(~r/mul\((\d+),(\d+)\)/, input)
|> Enum.map(fn [_, l, r] -> String.to_integer(l) * String.to_integer(r) end)
|> Enum.sum()

Part 2

# this is a very weird way way to go about this.

input
|> String.split("do()")
|> Enum.map(&String.split(&1, "don't()"))
# Invariant: Each element of the outer list starts with the parser enabled.
|> Enum.map(fn [head | _tail] ->
  # Parser should only be enabled for the first element.
  Regex.scan(~r/mul\((\d+),(\d+)\)/, head)
  |> Enum.map(fn [_, l, r] -> String.to_integer(l) * String.to_integer(r) end)
  |> Enum.sum()
end)
|> Enum.sum()