Day 02

Mix.install([
  {:kino, "~> 0.7.0"}
])

example_input =
  Kino.Input.textarea("example input:")
  |> Kino.render()

real_input = Kino.Input.textarea("real input:")

Common

scores = %{
  ?A => 1,
  ?B => 2,
  ?C => 3,
  ?X => 1,
  ?Y => 2,
  ?Z => 3
}

parse = fn input ->
  input
  |> Kino.Input.read()
  |> String.split("\n")
  |> Enum.map(fn str ->
    str
    |> String.to_charlist()
    |> then(fn [other, _, self] -> {other, self} end)
  end)
end

score = fn list ->
  list
  |> Enum.reduce(0, fn
    {m, m}, sum -> sum + m + 3
    {1, 3}, sum -> sum + 3
    {3, 1}, sum -> sum + 1 + 6
    {other, self}, sum when other > self -> sum + self
    {_other, self}, sum -> sum + self + 6
  end)
end

Part 1

convert = fn list ->
  list
  |> Enum.map(fn {other, self} -> {scores[other], scores[self]} end)
end

real_input
|> parse.()
|> convert.()
|> score.()

Part 2

convert = fn list ->
  list
  |> Enum.map(fn {other, self} -> {scores[other], self} end)
  |> Enum.map(fn
    {other, ?Y} -> {other, other}
    {1, ?X} -> {1, 3}
    {other, ?X} -> {other, other - 1}
    {3, ?Z} -> {3, 1}
    {other, ?Z} -> {other, other + 1}
  end)
end

real_input
|> parse.()
|> convert.()
|> score.()