2015/06/script.rb

#!/usr/bin/env ruby

require_relative '../common'

class LightGrid
  def initialize(brightness = false)
    @brightness = brightness
    @grid = Array.new(1000) { Array.new(1000, 0) }
  end

  def parse(instructions)
    instructions.each do |string|
      instruction, from_x, from_y, to_x, to_y = string.match(/\A(.*) ([0-9]+),([0-9]+) through ([0-9]+),([0-9]+)\z/).captures
      klass = instruction_klass(instruction)

      (from_x.to_i..to_x.to_i).each do |i|
        (from_y.to_i..to_y.to_i).each do |j|
          @grid[i][j] = klass.process(@grid[i][j])
        end
      end
    end

    @grid.flatten.sum
  end

  private

  def instruction_klass(instruction)
    if @brightness
      case instruction
      when "turn on"
        Brightness::TurnOn
      when "turn off"
        Brightness::TurnOff
      else
        Brightness::Toggle
      end
    else
      case instruction
      when "turn on"
        Simple::TurnOn
      when "turn off"
        Simple::TurnOff
      else
        Simple::Toggle
      end
    end
  end

  class Simple
    class TurnOn
      def self.process(value)
        1
      end
    end

    class TurnOff
      def self.process(value)
        0
      end
    end

    class Toggle
      def self.process(value)
        value == 1 ? 0 : 1
      end
    end
  end

  class Brightness
    class TurnOn
      def self.process(value)
        value + 1
      end
    end

    class TurnOff
      def self.process(value)
        value > 0 ? value - 1 : 0
      end
    end

    class Toggle
      def self.process(value)
        value + 2
      end
    end
  end
end

class Day6 < Day
  def part1
    LightGrid.new.parse input
  end

  def part2
    LightGrid.new(true).parse input
  end
end

Day6.run