Day 07

Setup

Mix.install([{:kino, "~> 0.4.1"}])

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

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

Part 1

real_input
|> Kino.Input.read()
|> String.split(",")
|> Enum.map(&String.to_integer/1)
|> then(fn list ->
  cost = fn target ->
    list
    |> Enum.map(&Kernel.-(&1, target))
    |> Enum.map(&Kernel.abs(&1))
    |> Enum.sum()
  end

  0..Enum.max(list)
  |> Enum.map(cost)
  |> Enum.min()
end)

Part 2

real_input
|> Kino.Input.read()
|> String.split(",")
|> Enum.map(&String.to_integer/1)
|> then(fn list ->
  triangle = fn n -> div(n * (n + 1), 2) end

  cost = fn target ->
    list
    |> Enum.map(&Kernel.-(&1, target))
    |> Enum.map(&Kernel.abs(&1))
    |> Enum.map(triangle)
    |> Enum.sum()
  end

  0..Enum.max(list)
  |> Enum.map(cost)
  |> Enum.min()
end)