this post was submitted on 02 Dec 2024
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Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

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

Solution Threads

M T W T F S S
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25

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console.log('Hello World')

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Day 2: Red-Nosed Reports

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[โ€“] aurele 1 points 3 weeks ago

Elixir

defmodule AdventOfCode.Solution.Year2024.Day02 do
  use AdventOfCode.Solution.SharedParse

  @impl true
  def parse(input) do
    for line <- String.split(input, "\n", trim: true),
        do: String.split(line) |> Enum.map(&String.to_integer/1)
  end

  def part1(input) do
    Enum.count(input, &is_safe(&1, false))
  end

  def part2(input) do
    Enum.count(input, &(is_safe(&1, true) or is_safe(tl(&1), false)))
  end

  def is_safe([a, b, c | rest], can_fix) do
    cond do
      (b - a) * (c - b) > 0 and abs(b - a) in 1..3 and abs(c - b) in 1..3 ->
        is_safe([b, c | rest], can_fix)

      can_fix ->
        is_safe([a, c | rest], false) or is_safe([a, b | rest], false)

      true ->
        false
    end
  end

  def is_safe(_, _), do: true
end