Day 1: Trebuchet?! – Advent of Code

input =
  File.stream!("/Users/pw/src/weiland/adventofcode/2023/input/01.txt")
  |> Stream.map(&String.trim/1)

Part One

defmodule PartOne do
  @doc """
      iex> test_input = String.split("1abc2
      ...>pqr3stu8vwx
      ...>a1b2c3d4e5f
      ...>treb7uchet", "\\n")
      iex> PartOne.solve(test_input)
      142
  """
  def solve(input) do
    input
    |> Stream.map(&String.replace(&1, ~r"[a-z]", ""))
    |> Stream.map(&String.to_integer/1)
    |> Stream.map(fn i -> if i <= 9, do: i + 10 * i, else: i end)
    |> Stream.map(&amp;Integer.digits/1)
    |> Stream.map(fn [h | t] -> "#{h}#{Enum.at(t, -1)}" |> String.to_integer() end)
    |> Enum.sum()
  end
end

ExUnit.start(auto_run: false)

defmodule PartTest do
  use ExUnit.Case, async: false
  doctest PartOne
end

ExUnit.run()

PartOne.solve(input)

Part Two

defmodule PartTwo do
  defp parse_numbers(input) do
    input
    |> Stream.map(&String.replace(&1, "one", "one1one"))
    |> Stream.map(&String.replace(&1, "two", "two2two"))
    |> Stream.map(&String.replace(&1, "three", "three3three"))
    |> Stream.map(&String.replace(&1, "four", "four4four"))
    |> Stream.map(&String.replace(&1, "five", "five5five"))
    |> Stream.map(&String.replace(&1, "six", "six6six"))
    |> Stream.map(&String.replace(&1, "seven", "seven7seven"))
    |> Stream.map(&String.replace(&1, "eight", "eight8eight"))
    |> Stream.map(&String.replace(&1, "nine", "nine9nine"))
  end

  @doc """
      iex> test_input_two = "two1nine
      ...>eightwothree
      ...>abcone2threexyz
      ...>xtwone3four
      ...>4nineeightseven2
      ...>zoneight234
      ...>7pqrstsixteen" |> String.split("\\n", trim: true)
      iex> PartTwo.solve(test_input_two)
      281
  """
  def solve(input) do
    input
    |> parse_numbers
    |> Stream.map(&String.replace(&1, ~r"[a-z]", ""))
    |> Stream.map(&String.to_integer/1)
    |> Stream.map(fn i -> if i <= 9, do: i + 10 * i, else: i end)
    |> Stream.map(&amp;Integer.digits/1)
    |> Stream.map(fn [h | t] -> "#{h}#{Enum.at(t, -1)}" |> String.to_integer() end)
    |> Enum.sum()
  end
end

ExUnit.start(auto_run: false)

defmodule PartTwoTest do
  use ExUnit.Case, async: false
  doctest PartTwo
end

ExUnit.run()

PartTwo.solve(input)