day1.livemd

Day 1

Setup

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

:ok

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

Part 1

height_list =
  input
  |> Kino.Input.read()
  |> String.trim()
  |> String.split("\n")
  |> Enum.map(&String.to_integer(&1))

process_input = fn height_list ->
  height_list
  |> Enum.zip([nil | height_list])
  |> Enum.map(fn
    {n, nil} -> {n, "N/A - no previous measurement"}
    {n, prev} when prev < n -> {n, "increased"}
    {n, prev} when prev > n -> {n, "decreased"}
    {n, n} -> {n, "equal"}
  end)
end

height_list
|> process_input.()
|> Enum.count(fn {_n, result} -> result == "increased" end)

1167

Part 2

sum_3 =
  height_list
  |> Enum.zip([nil | height_list])
  |> Enum.zip([nil | [nil | height_list]])
  |> Enum.drop(2)
  |> Enum.map(fn {{a, b}, c} -> a + b + c end)

sum_3
|> process_input.()
|> Enum.count(fn {_n, result} -> result == "increased" end)

1130