Historian Hysteria

Mix.install([{:kino, "~> 0.14.2"}])

Input

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

input = Kino.Input.read(input)

input =
  input
  |> String.trim()
  |> String.split("\n")
  |> Enum.map(fn x ->
    String.split(x) |> Enum.map(&String.to_integer/1)
  end)

{left, right} =
  Enum.reduce(input, {[], []}, fn [l, r], {left, right} -> {[l | left], [r | right]} end)

left = Enum.sort(left)
right = Enum.sort(right)

Part 1

Enum.zip(left, right)
|> Enum.reduce(0, fn {l, r}, sum ->
  distance = abs(l - r)
  sum + distance
end)

Part 2

Enum.reduce(left, 0, fn l, acc ->
  count = Enum.count(right, fn r -> l == r end)
  acc + l * count
end)