day7.livemd

Day 7

Setup

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

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

Modules

defmodule Crab do
  def total_fuel_aligning_at(crabs, pos) do
    crabs
    |> Enum.reduce(0, fn crab, fuel ->
      fuel + abs(crab - pos)
    end)
  end

  def total_inc_fuel_aligning_at(crabs, pos) do
    crabs
    |> Enum.reduce(0, fn crab, fuel ->
      distance = abs(crab - pos)
      consumption = Enum.sum(0..distance)

      consumption + fuel
    end)
  end
end

Part 1

crabs =
  input
  |> Kino.Input.read()
  |> String.split(",")
  |> Enum.map(&String.to_integer/1)

IO.inspect(crabs)

{min_pos, max_pos} = Enum.min_max(crabs)

fuels =
  min_pos..max_pos
  |> Enum.map(fn pos -> Crab.total_fuel_aligning_at(crabs, pos) end)

min_fuel = Enum.min(fuels)

Enum.with_index(fuels)
|> Enum.min()
|> elem(0)

Part 2

IO.inspect(crabs)

fuels =
  min_pos..max_pos
  |> Enum.map(fn pos -> Crab.total_inc_fuel_aligning_at(crabs, pos) end)

min_fuel = Enum.min(fuels)

Enum.with_index(fuels)
|> Enum.min()
|> elem(0)