require "./common.cr"

lines = File.read("day6_input").split("\n")
lines.pop

REGEX = /(\d+), (\d+)/
coords = lines.map(&.match(REGEX))
  .select { |it| it != nil }
  .map { |match| { match.not_nil![1].to_i32, match.not_nil![2].to_i32 } }

def distance(a, b)
  (a[0] - b[0]).abs + (a[1] - b[1]).abs
end

def compute_area(coords, coord)
  visited = Set(Tuple(Int32, Int32)).new
  total = 0

  coord_queue = Set(Tuple(Int32, Int32)).new
  coord_queue << coord

  while !coord_queue.empty?
    new_coord = coord_queue.first
    coord_queue.delete new_coord

    next if visited.includes? new_coord
    visited << new_coord

    distances = coords.group_by do |coord|
      distance(coord, new_coord)
    end
    min_distance = distances.keys.min

    next if distances[min_distance].size != 1
    next if distances[min_distance][0] != coord

    total += 1
    x, y = new_coord
    coord_queue << { x + 1, y }
    coord_queue << { x - 1, y }
    coord_queue << { x, y + 1 }
    coord_queue << { x, y - 1 }

    if total > 10000
      return 0
    end
  end

  return total
end

def find_region(coords)
  total = 0
  (-11000/2..11000/2).each do |x|
    (-11000/2..11000/2).each do |y|
      coord = {x, y}
      total += 1 if coords.sum { |it| distance(it, coord) } < 10000
    end
  end
  
  return total
end

puts coords.max_of { |it| compute_area(coords, it) }
puts find_region(coords)