Day 1: Trebuchet?!

Mix.install([{:kino, "~> 0.11.3"}])

Day 1

• Puzzle: https://adventofcode.com/2023/day/1
• Input: https://adventofcode.com/2023/day/1/input

sample_input = Kino.Input.textarea("Paste Sample Input")

real_input = Kino.Input.textarea("Paste Real Input")

defmodule Calibration do
  @digits Enum.map(0..9, &Integer.to_string/1)

  def sum(input) do
    input
    |> Kino.Input.read()
    |> String.split("\n", trim: true)
    |> Enum.map(&extract_digits/1)
    |> Enum.sum()
  end

  defp extract_digits(line) do
    tens = first_digit(line, :forward) * 10
    ones = line |> String.reverse() |> first_digit(:backward)
    tens + ones
  end

  def first_digit(<>, _) when h in @digits,
    do: String.to_integer(h)

  def first_digit("zero" <> _rest, :forward), do: 0
  def first_digit("one" <> _rest, :forward), do: 1
  def first_digit("two" <> _rest, :forward), do: 2
  def first_digit("three" <> _rest, :forward), do: 3
  def first_digit("four" <> _rest, :forward), do: 4
  def first_digit("five" <> _rest, :forward), do: 5
  def first_digit("six" <> _rest, :forward), do: 6
  def first_digit("seven" <> _rest, :forward), do: 7
  def first_digit("eight" <> _rest, :forward), do: 8
  def first_digit("nine" <> _rest, :forward), do: 9
  def first_digit("orez" <> _rest, :backward), do: 0
  def first_digit("eno" <> _rest, :backward), do: 1
  def first_digit("owt" <> _rest, :backward), do: 2
  def first_digit("eerht" <> _rest, :backward), do: 3
  def first_digit("ruof" <> _rest, :backward), do: 4
  def first_digit("evif" <> _rest, :backward), do: 5
  def first_digit("xis" <> _rest, :backward), do: 6
  def first_digit("neves" <> _rest, :backward), do: 7
  def first_digit("thgie" <> _rest, :backward), do: 8
  def first_digit("enin" <> _rest, :backward), do: 9
  def first_digit(<<_h::binary-size(1), rest::binary>>, dir), do: first_digit(rest, dir)
  def first_digit("", _), do: 0
end

Calibration.sum(sample_input)

Calibration.sum(real_input)