day11part2.rb

file = File.open "day11in.txt"

galaxies = {}
x = 0
y = 0
id = 0
file.each_line do |l|
  x = 0
  l.chomp.split("").each do |c|
    galaxies["#{x},#{y}"] = { x: x, y: y, id: (id += 1) } if c == "#"
    x += 1
  end
  y += 1
end
rows_to_expand = []
columns_to_expand = []
y.times do |temp_y|
  any_galaxies = false
  x.times do |temp_x|
    any_galaxies |= galaxies.include?("#{temp_x},#{temp_y}")
  end
  rows_to_expand << temp_y unless any_galaxies
end
x.times do |temp_x|
  any_galaxies = false
  y.times do |temp_y|
    any_galaxies |= galaxies.include?("#{temp_x},#{temp_y}")
  end
  columns_to_expand << temp_x unless any_galaxies
end
bao_expansion_coefficient = 999999
galaxies.each do |k, v|
  x_expansion = columns_to_expand.find_all { |it| it < v[:x] }.length * bao_expansion_coefficient
  y_expansion = rows_to_expand.find_all { |it| it < v[:y] }.length * bao_expansion_coefficient
  v[:x_expansion] = x_expansion
  v[:y_expansion] = y_expansion
end
galaxies = galaxies.map { |kv| kv[1] }
sum = 0

galaxies[..-2].each_with_index do |va, i|
  galaxies[(i + 1)..].each do |vb|
    dist = ((va[:x] + va[:x_expansion]) - (vb[:x] + vb[:x_expansion])).abs + ((va[:y] + va[:y_expansion]) - (vb[:y] + vb[:y_expansion])).abs
    sum += dist
  end
end
file.close
puts sum