Day 8: Haunted Wasteland

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[-] morrowind@lemmy.ml 2 points 2 years ago* (last edited 2 years ago)

Crystal

!crystal_lang@lemmy.ml

part 1 was made way simpler after I made it a function for part 2
also I accidentally saw someone elses code, so I can't take full credit for figuring out how to do part 2

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

Dirs = Input[0].chars.map {|c| c == 'L' ? 0 : 1}
Nodes = Hash(String, Tuple(String, String)).new
Input[2..].each {|line| Nodes[line[..2]] = {line[7..9], line[12..14]} }

# part 1
puts num_steps("AAA", &amp;.== "ZZZ")

# part 2
currents = Nodes.keys.select(&amp;.ends_with? 'A')
steps = currents.map {|cur| num_steps(cur, &amp;.ends_with? 'Z')}
puts steps.reduce(1_i64) {|a, b| a.lcm b}

def num_steps(start)
	steps = 0
	Dirs.cycle do |dir|
		steps += 1
		start = Nodes[start][dir]
		break if yield start
	end
	steps
end

this post was submitted on 08 Dec 2023

21 points (100.0% liked)

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