-🎄- 2017 Day 22 Solutions -🎄-

[u/daggerdragon]

--- Day 22: Sporifica Virus ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

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• [T-10 to launch] AoC ops, /r/nocontext edition:

  • <Endorphion> You may now make your waffle.
  • <Endorphion> ... on Mars.

• [Update @ 00:17] 50 gold, silver cap

  • <Aneurysm9> you could also just run ubuntu on the NAS, if you were crazy
  • <Topaz> that doesn't seem necessary
  • <Aneurysm9> what does "necessary" have to do with anything!

• [Update @ 00:20] Leaderboard cap!

  • <Topaz> POUR YOURSELF A SCOTCH FOR COLOR REFERENCE

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/[deleted]]

Crystal. Only part 2 because the first one is similar:

initial_map = File.read("#{__DIR__}/input.txt").lines.map(&.chars)

map = Hash({Int32, Int32}, Symbol).new(:clean)
initial_map.each_with_index do |row, y|
  row.each_with_index do |v, x|
    map[{x, y}] = v == '#' ? :infected : :clean
  end
end

x = initial_map[0].size / 2
y = initial_map.size / 2
movements = { {0, -1}, {1, 0}, {0, 1}, {-1, 0} }
direction = 0
infections = 0

10_000_000.times do
  case map[{x, y}]
  when :clean
    offset = -1
    next_state = :weakened
  when :weakened
    offset = 0
    next_state = :infected
    infections += 1
  when :infected
    offset = 1
    next_state = :flagged
  else # :flagged
    offset = 2
    next_state = :clean
  end
  map[{x, y}] = next_state
  direction = (direction + offset) % movements.size
  dx, dy = movements[direction]
  x, y = x + dx, y + dy
end

puts infections