gistfile1.rb

class Field
  attr_reader :length, :width, :bad_points

  include Enumerable
  def initialize length, width
    @length = length
    @width = width
    @bad_points = []
  end

  def add_bad_point x, y
    @bad_points << [x, y]
  end

  def each
    (1...length).each do |left|
      (1...width).each do |top|
        ((left + 1)..length).each do |right|
          ((top + 1)..width).each do |bottom|
            yield left, top, right, bottom if valid? left, top, right, bottom
          end
        end
      end
    end
  end

  def valid? x1, y1, x2, y2
    bad_points.each do |bad_point|
      x, y = bad_point
      if x == x1 or x == x2
        return false if (y1..y2).include? y
      elsif y == y1 or y == y2
        return false if (x1..x2).include? x
      end
    end
    true
  end

end