Advent of Code 2021 - Day 22

bjorng · December 22, 2021, 7:02am

This topic is about Day 22 of the Advent of Code 2021.

We have a private leaderboard (shared with users of Erlang Forums):

https://adventofcode.com/2021/leaderboard/private/view/370884

The entry code is:
370884-a6a71927

bjorng · December 22, 2021, 7:04am

Here is my solution:

github.com

bjorng/advent-of-code-2021/blob/6156d9705f72954f81310447fa0db4a85874d3d2/day22/lib/day22.ex

defmodule Day22 do
  def part1(input) do
    parse(input)
    |> Enum.reject(fn {_, {xr, yr, zr}} ->
      Enum.any?([xr, yr, zr], fn r ->
        r.first < -50 || r.last > 50
      end)
    end)
    |> solve
  end

  def part2(input) do
    solve(parse(input))
  end

  def solve(operations) do
    cuboids = []
    operations
    |> Enum.reduce(cuboids, &execute/2)
    |> Enum.reduce(0, fn {xr, yr, zr}, count ->

This file has been truncated. show original

princemaple · December 22, 2021, 7:18am

github.com

princemaple/aoc/blob/main/2021/day22.exs

# Title: Day22

# ── Untitled ──

data =
  "input"
  |> IO.getn(1_000_000)
  |> String.trim()
  |> String.split(["\r\n", "\n"], trim: true)
  |> Enum.map(fn line ->
    line
    |> String.split()
    |> then(fn [on_off, coords] ->
      coords
      |> String.replace(~r/x=|y=|z=/, "")
      |> String.split(",")
      |> Enum.map(&Code.eval_string/1)
      |> Enum.map(&elem(&1, 0))
      |> then(&{on_off == "on", &1})
    end)

This file has been truncated. show original

dallagi · December 22, 2021, 12:07pm

Here’s mine

github.com

dallagi/aoc2021/blob/main/lib/aoc2021/day22.ex

defmodule Aoc2021.Day22 do
  def part1(input) do
    input
    |> parse
    |> Enum.filter(fn {_action, ranges} ->
      Enum.all?(ranges, fn from..to -> from in -50..50 and to in -50..50 end)
    end)
    |> cubes_on_after_init_procedure()
  end

  def part2(input) do
    input
    |> parse
    |> cubes_on_after_init_procedure()
  end

  def cubes_on_after_init_procedure(steps) do
    {cubes_on_count, _} =
      for {action, cube} <- Enum.reverse(steps),
          reduce: {0, []} do

This file has been truncated. show original

lud · December 22, 2021, 5:45pm

I see you are using ranges I don’t even understand properly what Range.disjoint? means. So I just wrote all the cases. It’s still short enough.

Anyway here is my version, I’m splitting cubes too : adventofcode/day_22.ex at main · lud/adventofcode · GitHub
It took a couple minutes to run, but when I removed all IO.inspect and other printouts, it runs in 23ms

It’s very infortunate that max contains the letter “x” so instead of using xmax names I used xi and xo for minimum x and maximum x, respectively. (“i” as in “min” and “o” for omega ).

ramuuns · December 22, 2021, 5:47pm

I did absolutely enjoy today, especially that AHA moment that I got after coming up with a possible solution in my head. That said the cube splitting took a while to properly implement.

github.com

ramuuns/aoc/blob/de3e7a8/2021/day-22.ex

defmodule Day22 do
  def run(mode) do
    data = read_input(mode)

    {
      data |> part1(),
      data |> part2()
    }
  end

  def read_input(:test) do
    "on x=-20..26,y=-36..17,z=-47..7
on x=-20..33,y=-21..23,z=-26..28
on x=-22..28,y=-29..23,z=-38..16
on x=-46..7,y=-6..46,z=-50..-1
on x=-49..1,y=-3..46,z=-24..28
on x=2..47,y=-22..22,z=-23..27
on x=-27..23,y=-28..26,z=-21..29
on x=-39..5,y=-6..47,z=-3..44
on x=-30..21,y=-8..43,z=-13..34

This file has been truncated. show original