Advent of code day 06

Mix.install([
  {:kino, "~> 0.5.0"}
])

Setup input

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

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

Helpers

Part 01

## BRUTE FORCE

fishes =
  example
  |> Kino.Input.read()
  |> String.split(",", trim: true)
  |> Enum.map(&String.to_integer/1)

1..80
|> Enum.reduce(fishes, fn _el, acc ->
  ## count zeros 
  zeros = Enum.count(acc, fn e -> e == 0 end)
  eights = if zeros == 0, do: [], else: Enum.map(1..zeros, fn _eight -> 8 end)
  ## sub -1 from every fish 
  acc = Enum.map(acc, fn n -> if n == 0, do: 6, else: n - 1 end)
  ## add eights 

  acc ++ eights
end)
|> Enum.count()

Part 02

# OPTIMIZED USING HASH MAPPURU

fishes =
  input
  |> Kino.Input.read()
  |> String.split(",", trim: true)
  |> Enum.map(&String.to_integer/1)
  |> Enum.frequencies()

1..256
|> Enum.reduce(fishes, fn _el, acc ->
  zeros = Map.get(acc, 0, 0)

  outside = acc

  acc =
    7..0
    |> Enum.reduce(acc, fn key, acc ->
      Map.put(acc, key, Map.get(outside, key + 1, 0))
    end)

  acc = Map.put(acc, 8, zeros)
  Map.put(acc, 6, Map.get(outside, 7, 0) + zeros)
end)
|> Map.values()
|> Enum.sum()