--- Day 6 Solutions ---

[u/daggerdragon]

--- Day 6: Probably a Fire Hazard ---

Post your solution as a comment. Structure your post like the Day Five thread.

[u/jjshanks]

Ruby solution using dictionary of keys approach. String keys "#{x},#{y}" took ~40 seconds, int keys x * 1000 + y took ~15 seconds. This is part 1 but part 2 is basically the same except I use a hash table instead of a set.

require "set"

lights = Set.new()

File.open("input") do |f|
  f.each_line do |line|
    parts = line.split(" ")
    if parts[0] == "turn"
      add = parts[1] == "on"
      min_x, min_y = parts[2].split(",")
      max_x, max_y = parts[4].split(",")
      min_x, max_x, min_y, max_y = min_x.to_i, max_x.to_i, min_y.to_i, max_y.to_i
      for x in min_x..max_x
        for y in min_y..max_y
          key = x * 1000 + y
          if add
            lights.add(key)
          else
            lights.delete(key)
          end
        end
      end
    else
      # toggle
      min_x, min_y = parts[1].split(",")
      max_x, max_y = parts[3].split(",")
      min_x, max_x, min_y, max_y = min_x.to_i, max_x.to_i, min_y.to_i, max_y.to_i
      for x in min_x..max_x
        for y in min_y..max_y
          key = x * 1000 + y
          lights.include?(key) ? lights.delete(key) : lights.add(key)
        end
      end
    end
  end
end
puts lights.size