Advent Of Code

920 readers

87 users here now

An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

Solution Threads

M	T	W	T	F	S	S
						1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25

Rules/Guidelines

Follow the programming.dev instance rules
Keep all content related to advent of code in some way
If what youre posting relates to a day, put in brackets the year and then day number in front of the post title (e.g. [2024 Day 10])
When an event is running, keep solutions in the solution megathread to avoid the community getting spammed with posts

Relevant Communities

Relevant Links

Advent of Code Homepage

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 1 year ago

MODERATORS

[email protected]

☃️ - 2023 DAY 11 SOLUTIONS - ☃️ (programming.dev)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

19 comments fedilink hide all child comments

Day 11: Cosmic Expansion

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/ , pastebin, or github (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

What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
Where do I participate?: https://adventofcode.com/
Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

🔒 Thread is locked until there's at least 100 2 star entries on the global leaderboard

🔓 Unlocked after 9 mins

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 2 points 1 year ago

Crystal

[email protected]

wording in part 2 threw me off too

I could have done this in 2 loops, but this method is way easier to do
And it's gorgeous code imo
(except for the fact that lemmy's huge tab sizes make it look weird)

code

E = ARGV[0].to_i

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

sky = input.lines.map &amp;.chars

# find galaxies
galaxies = Array(Tuple(Int32, Int32)).new
sky.size.times do |y| 
	sky[0].size.times do |x|
		if sky[y][x] == '#'
			galaxies &lt;&lt; {y, x}
end     end     end
# puts galaxies

# vertical expansion locations
expandsy = Array(Int32).new
sky.size.times do |i|
	unless galaxies.any? {|gal| gal[0] == i}
		expandsy &lt;&lt; i
end     end

# horizontal expansion locations
expandsx = Array(Int32).new
sky[0].size.times do |i|
	unless galaxies.any? {|gal| gal[1] == i}
		expandsx &lt;&lt; i
end     end

# calculate expansion for each galaxy
adds = Array.new(galaxies.size) { [0, 0] }
expandsy.each do |y|
	galaxies.each_with_index do |gal, i|
		if gal[0] > y
			adds[i][0] += 1
end     end     end

# calculate expansion for each galaxy
expandsx.each do |x|
	galaxies.each_with_index do |gal, i|
		if gal[1] > x
			adds[i][1] += 1
end     end     end

# expaaaaaaaand
galaxies.map_with_index! {|gal, i| {gal[0] + adds[i][0]*E, gal[1] + adds[i][1]*E} }

# distances
sum = 0_u64
galaxies.each do |gal|
	galaxies.each do |gal2|
		if gal2 != gal
			sum += (gal2[0] - gal[0]).abs + (gal2[1] - gal[1]).abs
end     end     end
puts sum/2