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| 1 | +defmodule AdventOfCode.Y2024.Day03 do |
| 2 | + @moduledoc """ |
| 3 | + --- Day 3: Mull It Over --- |
| 4 | + Problem Link: https://adventofcode.com/2024/day/3 |
| 5 | + Difficulty: |
| 6 | + Tags: |
| 7 | + """ |
| 8 | + alias AdventOfCode.Helpers.{InputReader, Transformers} |
| 9 | + |
| 10 | + def input, do: InputReader.read_from_file(2024, 3) |
| 11 | + |
| 12 | + def run(input \\ input()) do |
| 13 | + input = parse(input) |
| 14 | + |
| 15 | + {run_1(input), run_2(input)} |
| 16 | + end |
| 17 | + |
| 18 | + defp run_1(input) do |
| 19 | + input |
| 20 | + |> Enum.flat_map(fn line -> line |> tokenize() |> Enum.map(&mul/1) end) |
| 21 | + |> Enum.sum() |
| 22 | + end |
| 23 | + |
| 24 | + defp run_2(input) do |
| 25 | + input |
| 26 | + |> Enum.flat_map(&tokenize_with_state/1) |
| 27 | + |> Enum.reduce({true, 0}, fn instruction, {continue?, total} -> |
| 28 | + case {continue?, instruction} do |
| 29 | + {_, "do()"} -> {true, total} |
| 30 | + {_, "don't()"} -> {false, total} |
| 31 | + {true, instruction} -> {true, mul(instruction) + total} |
| 32 | + {false, _} -> {false, total} |
| 33 | + end |
| 34 | + end) |
| 35 | + |> elem(1) |
| 36 | + end |
| 37 | + |
| 38 | + def parse(data \\ input()) do |
| 39 | + data |
| 40 | + |> Transformers.lines() |
| 41 | + end |
| 42 | + |
| 43 | + def tokenize_with_state(line) do |
| 44 | + ~r/(?>mul\(\d+,\d+\))|(?>do\(\))|(?>don't\(\))/ |
| 45 | + |> Regex.scan(line) |
| 46 | + |> List.flatten() |
| 47 | + end |
| 48 | + |
| 49 | + def tokenize(line) do |
| 50 | + ~r/mul\(\d+,\d+\)/ |
| 51 | + |> Regex.scan(line) |
| 52 | + |> List.flatten() |
| 53 | + end |
| 54 | + |
| 55 | + def mul(token) do |
| 56 | + token |
| 57 | + |> String.replace("mul(", "") |
| 58 | + |> String.replace(")", "") |
| 59 | + |> String.split(",") |
| 60 | + |> Enum.map(&String.to_integer/1) |
| 61 | + |> Enum.reduce(&(&1 * &2)) |
| 62 | + end |
| 63 | +end |
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