Day 3

Section

path = "Projects/aoc/2022/day3.txt"
input = File.read!(path)

defmodule Day3 do
  def part1(input) do
    input
    |> String.split()
    |> Enum.map(fn x ->
      {l1, l2} = String.split_at(x, div(String.length(x), 2))

      String.codepoints(l1)
      |> Enum.reject(fn x ->
        !String.contains?(l2, x)
      end)
      |> Enum.uniq()
    end)
    |> List.flatten()
    |> Enum.reduce(0, fn x, acc ->
      acc + (x |> String.to_charlist() |> hd |> calc_pts)
    end)
  end

  def part2(input) do
    input
    |> String.split()
    |> Enum.chunk_every(3)
    |> Enum.map(fn [x, y, z] = l ->
      (x <> y <> z)
      |> String.codepoints()
      |> Enum.uniq()
      |> Enum.sort()
      |> Enum.filter(fn c ->
        Enum.all?(l, fn x ->
          String.contains?(x, c)
        end)
      end)
    end)
    |> List.flatten()
    |> Enum.reduce(0, fn x, acc ->
      acc + (x |> String.to_charlist() |> hd |> calc_pts)
    end)
  end

  def calc_pts(char) when char in ?a..?z do
    char - 96
  end

  def calc_pts(char) when char in ?A..?Z do
    char - 38
  end
end

Day3.part1(input)
Day3.part2(input)