Advent of Code 2023 day011.rb

day011.rb

require_relative "main"

module Day011
  INPUT = File.read('INPUT.txt')

  grid = INPUT.to_grid

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

  empty_rows = (0...grid.y_length).filter_map do |y|
    (grid.row(y).all? { _1 == "." }) ? y : nil
  end

  empty_cols = (0...grid.x_length).filter_map do |x|
    (grid.column(x).all? { _1 == "." }) ? x : nil
  end

  # @type [Array[V]]
  galaxies = []
  grid.each do |v, value|
    galaxies.push(v) if value == "#"
  end

  t1 = 0
  t2 = 0

  i = 0
  while i < galaxies.length
    j = i + 1
    while j < galaxies.length
      a = galaxies[i]
      b = galaxies[j]

      x_expand = ([a.x, b.x].min..[a.x, b.x].max).to_a.filter { empty_cols.include?(_1) }.count
      y_expand = ([a.y, b.y].min..[a.y, b.y].max).to_a.filter { empty_rows.include?(_1) }.count

      manhattan = (b - a).manhattan

      t1 += x_expand + y_expand + manhattan
      t2 += x_expand * (1000000 - 1) + y_expand * (1000000 - 1) + manhattan
      j += 1
    end
    i += 1
  end

  answer1 = t1

  pp answer1

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

  answer2 = t2

  pp answer2
end