Advent of Code 2023 day003.rb

day003.rb

require_relative "main"

module Day003
  INPUT = File.read('INPUT.txt')

  grid = INPUT.to_grid

  ##########
  # Part 1 #
  ##########

  symbol_locations = []
  number_locations = []
  grid.each do |v, value|
    if value != "."
      target = value.is_09? ? number_locations : symbol_locations
      target.push(v)
    end
  end

  groups = []
  number_locations.each do |v|
    if groups.last&.last == v.left
      groups.last.push(v)
    else
      groups.push([v])
    end
  end

  valid_groups = groups.filter do |group|
    group.reduce(false) do |memo, v|
      memo || grid.eight(v).any? { symbol_locations.include?(_1) }
    end
  end

  answer1 = valid_groups.reduce(0) do |memo, group|
    memo + grid.get_values(group).join.to_i
  end

  pp answer1

  ##########
  # Part 2 #
  ##########

  answer2 = symbol_locations.reduce(0) do |memo, v_s|
    if grid.get_value(v_s) == '*'
      adjacent_groups = groups.filter do |group|
        group.reduce(false) do |memo, v|
          memo || v.eight.include?(v_s)
        end
      end

      if adjacent_groups.count == 2
        memo += adjacent_groups.map do |group|
          grid.get_values(group).join.to_i
        end.arith_prod
      end
    end

    memo
  end

  pp answer2
end