NobbZ

Advent of Code - Day 3

Note by the Moderators: This topic is to talk about Day 3 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.

And day 3 is solved as well.

On my VM in the office both parts take about 1 to 1.25 seconds. Thats OK for me today. But the first iteration I used to get the actual solutions has some repitions in it, which I do not like.

I really have to iterate on those, and perhaps I’ll be even able to get them more efficient?

gitlab.com

NobbZ/aoc_ex/blob/master/lib/y2018/d3.ex

defmodule AocEx.Y2018.D3 do
  use AocEx.Boilerplate,
    transform: fn raw ->
      raw
      |> String.split("\n")
      |> Enum.map(&String.split/1)
      |> Enum.map(fn ["#" <> id, "@", coord, size] ->
        id = String.to_integer(id)

        coord =
          coord
          |> String.trim(":")
          |> String.split(",")
          |> Enum.map(&String.to_integer/1)
          |> List.to_tuple()

        size =
          size
          |> String.split("x")
          |> Enum.map(&String.to_integer/1)

This file has been truncated. show original

4 comments

#coding-challenge #2018 #advent-of-code

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2018-12-04 08:38:29 UTC

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yawaramin

I approached Day 3 as a set intersection problem, the only issue was finding a data structure to represent the claims that would be usable as set elements (i.e. comparable for uniqueness). I realized I could cleanly map each claim to a set of coordinates of the exact square inches of that claim; after that the solution fell into place as a series of set intersections and unions.

Here it is: https://github.com/yawaramin/advent_of_code_2018/blob/d65581aeb7b25f40d22a05c1435b1401b2505fef/lib/day3.ex

Btw, I thought I’d share this fun fact that Elixir is in the top ten (at 10th) languages being used for Advent of Code projects on GitHub: https://github.com/search?o=desc&q=advent+of+code&s=updated&type=Repositories

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#coding-challenge #2018 #advent-of-code

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NobbZ

Advent of Code - Day 3

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yawaramin

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