Day 4: Scratchcards

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ or pastebin (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)

FAQ

🔒This post will be unlocked when there is a decent amount of submissions on the leaderboard to avoid cheating for top spots

🔓 Unlocked after 8 mins

  • morrowind@lemmy.ml
    2·
    11 months ago

    Crystal

    late because I had to skip two days of aoc. Fairly easy

    input =  File.read("input.txt").lines

sum = 0
winnings = Array.new(input.size) {[1, 0]}
input.each_with_index do |line, i|
	card, values = line.split(":")
	nums = values.split("|").map(&.split.map(&.to_i))

	points = 0
	nums[1].each do |num|
		if nums[0].includes?(num)
			points = points == 0 ? 1 : points * 2
			winnings[i][1] += 1
	end    end
	sum += points
end
puts sum

winnings.each_with_index do |card, i|
	next if card[1] == 0
	(1..card[1]).each do |n|
		winnings[i+n][0] += card[0]
end    end
puts winnings.sum(&.[0])