Advent of Code - Day 13

sasajuric · December 13, 2018, 4:05pm

Note: This topic is to talk about Day 13 of the Advent of Code.

For general discussion about the Advent of Code 2018 and links to topics of the other days, see this topic.

sasajuric · December 13, 2018, 4:07pm

I found today’s task somewhat tedious. I lost some time because I didn’t cover the case where the cars crash in the middle of the tick, so I got wrong results. Anyway, my solution is here.

simon · December 14, 2018, 1:00am

I need to do some serious refactoring and tidying up and I’ve only completed part 1 so far but my solution is here.

Part 2 should be pretty simple to solve but my guess about it involving tracking the number of ticks was wrong so I can also tidy my code up because of that a bit too.

My biggest gotcha was in that I copied and pasted my file reading code from a previous day and was trimming it so my grid was all out of alignment.

I’ll add the part two solution tomorrow morning.

JEG2 · December 14, 2018, 2:30pm

My solution to Day 13:

github.com

JEG2/advent_of_code_2018/blob/master/day_13/mine_cart_madness.exs

defmodule MineCartMadness do
  defstruct tracks: Map.new, carts: [ ], moved: [ ]

  defmodule Cart do
    defstruct facing: nil, location: nil, turns: ~w[left straight right]a

    def new("<", location) do
      %__MODULE__{facing: :left, location: location}
    end
    def new(">", location) do
      %__MODULE__{facing: :right, location: location}
    end
    def new("^", location) do
      %__MODULE__{facing: :up, location: location}
    end
    def new("v", location) do
      %__MODULE__{facing: :down, location: location}
    end

    def move(cart, tracks) do

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You can watch me create it in this video (for the next 14 days):

bjorng · December 14, 2018, 7:55pm

My solution to Day 13. I struggled with collision detection for a long time. Here is the cleaned up version of my code.

sfusato · December 15, 2018, 2:52pm

I struggled with this one. It was also a pain in the ass to debug what was wrong with the state I was building at each tick. I wish they gave more test cases to cover rather than the default one as that one was passing.

My solution is here.

snewcomer · December 16, 2018, 6:11am

Laborious but interesting!

github.com

snewcomer/advent-of-code-elixir/blob/master/day13/lib/day13.ex

defmodule Day13 do

  @carts [">", "<", "v", "^"]

  def part1(input) do
    lines =
      input
      |> File.read!()
      |> String.trim_trailing()
      |> String.split("\n", trim: true)

    point_map =
      lines
      |> register_points_in_grid()

    carts =
      lines
      |> build_cart_positions(point_map)
      |> Enum.sort()

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simon · December 21, 2018, 12:26am

It wasn’t and I ended up also retro-fitting the part 2 solution to handle part 1 too. However the updated code can all be found here.

marekciupak · January 16, 2019, 8:17pm