Day 9

Deps & preparation

Mix.install([
  {:kino, "~> 0.4.0"}
])

input = Kino.Input.textarea("Please paste your input file:")

Input

heightmap =
  Kino.Input.read(input)
  |> String.split(~r{\.*|\s}, trim: true)
  |> Enum.map(&String.to_integer/1)

# |> Enum.chunk_every(10)
# |> Enum.chunk_every(100)

Part 1

lows =
  heightmap
  |> Enum.with_index()
  |> Enum.reduce([], fn {x, index}, acc ->
    #     -100
    # -1    x   +1
    #     +100
    up = Enum.at(heightmap, index - 100)
    down = Enum.at(heightmap, index + 100)
    left = Enum.at(heightmap, index - 1)
    right = Enum.at(heightmap, index + 1)

    if x < Enum.min([up, down, left, right]), do: [x | acc], else: acc
  end)

Enum.count(lows) + Enum.sum(lows)

Part 2

# Utilize group_by and group by basil size?
# prob bullshit now that I think about it