Day 02

Input

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

input_arr =
  input
  |> Kino.Input.read()
  |> String.split("\n", trim: true)
  |> Enum.map(fn
    "forward " <> num -> {:forward, num}
    "down " <> num -> {:down, num}
    "up " <> num -> {:up, num}
  end)
  |> Enum.map(fn {dir, n} -> {dir, String.to_integer(n)} end)

[
  forward: 6,
  down: 8,
  down: 5,
  down: 9,
  forward: 2,
  down: 5,
  down: 5,
  forward: 1,
  forward: 7,
  down: 8,
  up: 2,
  down: 4,
  up: 8,
  down: 8,
  forward: 3,
  forward: 4,
  down: 1,
  forward: 5,
  up: 7,
  down: 7,
  down: 8,
  forward: 2,
  up: 3,
  forward: 1,
  forward: 6,
  forward: 9,
  forward: 7,
  forward: 8,
  forward: 2,
  forward: 3,
  up: 2,
  up: 8,
  down: 1,
  forward: 7,
  down: 7,
  down: 2,
  forward: 6,
  down: 1,
  forward: 5,
  down: 3,
  forward: 6,
  down: 7,
  up: 1,
  up: 3,
  forward: 7,
  forward: 6,
  forward: 8,
  down: 4,
  down: 2,
  up: 5,
  ...
]

Problem 01

{x, y} =
  input_arr
  |> Enum.reduce(
    {0, 0},
    fn
      {:forward, n}, {x, y} -> {x + n, y}
      {:up, n}, {x, y} -> {x, y - n}
      {:down, n}, {x, y} -> {x, y + n}
    end
  )

{1890, 1172}

Output

x * y

2215080

Problem 02

{x, y, aim} =
  input_arr
  |> Enum.reduce(
    {0, 0, 0},
    fn
      {:forward, n}, {x, y, aim} -> {x + n, y + aim * n, aim}
      {:up, n}, {x, y, aim} -> {x, y, aim - n}
      {:down, n}, {x, y, aim} -> {x, y, aim + n}
    end
  )

{1890, 986622, 1172}

Output

x * y

1864715580