pascals_triangle.rb

class Triangle
  attr_reader :number_of_rows

  def initialize(number_of_rows)
    @number_of_rows = number_of_rows
  end

  def rows
    if number_of_rows == 1
      [[1]]
    else
      top_triangle = Triangle.new(number_of_rows - 1)
      previous_row = top_triangle.rows[-1]
      new_row = Array.new(previous_row.size + 1) do |index|
        case
        when index == 0 || index == previous_row.size
          1
        else
          previous_row[index - 1] + previous_row[index]
        end
      end
      top_triangle.rows << new_row
    end
  end



  # def initialize(num)
  #   @rows = [[1]]
  #   counter = 1
  #   until counter == num
  #     prev_row = @rows[-1]
  #     counter += 1
  #     new_row = Array.new(counter) do |index|
  #       case
  #       when index == 0 || index == counter - 1
  #         1
  #       else
  #         prev_row[index - 1] + prev_row[index]
  #       end
  #     end
  #     @rows << new_row
  #   end
  # end
  #
  # def rows
  #   @rows
  # end

end