this post was submitted on 03 Dec 2024
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Advent Of Code

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Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

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Day 3: Mull It Over

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[–] rwdf 2 points 1 day ago* (last edited 1 day ago) (1 children)

Elixir

First time writing Elixir. It's probably janky af.

I've had some help from AI to get some pointers along the way. I'm not competing in any way, just trying to learn and have fun.

~~Part 2 is currently not working, and I can't figure out why. I'm trying to just remove everything from "don't()" to "do()" and just pass the rest through the working solution for part 1. Should work, right?

Any pointers?~~

edit; working solution:

defmodule Three do
  def get_input do
    File.read!("./input.txt")
  end

  def extract_operations(input) do
    Regex.scan(~r/mul\((\d{1,3}),(\d{1,3})\)/, input)
    |> Enum.map(fn [_op, num1, num2] ->
      num1 = String.to_integer(num1)
      num2 = String.to_integer(num2)
      [num1 * num2]
    end)
  end

  def sum_products(ops) do
    List.flatten(ops)
    |> Enum.filter(fn x -> is_integer(x) end)
    |> Enum.sum()
  end

  def part1 do
    extract_operations(get_input())
    |> sum_products()
  end

  def part2 do
    String.split(get_input(), ~r/don\'t\(\)[\s\S]*?do\(\)/)
    |> Enum.map(&extract_operations/1)
    |> sum_products()
  end
end

IO.puts("part 1: #{Three.part1()}")
IO.puts("part 2: #{Three.part2()}")

[–] vole 3 points 1 day ago (1 children)

Part 2 is currently not working, and I can’t figure out why. I’m trying to just remove everything from β€œdon’t()” to β€œdo()” and just pass the rest through the working solution for part 1. Should work, right?

I think I had the same issue. Consider what happens if there isn't a do() after a don't().

[–] rwdf 1 points 1 day ago (1 children)

Ah, yes, that's it. The lazy solution would be to add a "do()" to the end of the input, right? Haha

[–] rwdf 1 points 1 day ago

It was actually a line break that broke the regex. Changing from a "." to "[\s\S]" fixed it.