Day 3: Gear Ratios

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

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  • @[email protected]
    2•1 year ago

    Crystal

    My computer crashed right most of the way through and I lost everything, so this was even more frustrating than it should have been
    Also damn, lemmy’s tabs are massive

    will post part 2 when I get to it

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

lines = input.lines.map(&.chars)

sum = 0
num_marker = nil
lines.each_with_index do |line, y|
	line.each_with_index do |char, x|
		num_marker ||= x if char.number?
	
		if (!char.number? || x == line.size-1) && num_marker
			if check_symbol(y, (num_marker-1)..x, lines)
				sum += lines[y][(char.number? ? num_marker..x : num_marker...x)].join.to_i 
			end
			num_marker = nil
end end end
puts sum

def check_symbol(y, rx, lines)
	carr = [ lines[y][rx.begin]?, lines[y][rx.end]? ]
	carr += rx.map {|x| lines[y-1][x]? } if y > 0  
	carr += rx.map {|x| lines[y+1][x]? } if y < lines.size-1 

	carr.each {|c| return true if c && c != '.' && !c.number?}
	false
end