ラーメンマーク

ramen.rb

class DirectionGenerator
  RIGHT = [ 0,  1]
  DOWN  = [ 1,  0]
  LEFT  = [ 0, -1]
  UP    = [-1,  0]
  def each
    [RIGHT, DOWN, LEFT, UP].cycle.each do |dir|
      yield dir
    end
  end
  
  def reverse_each
    [DOWN, RIGHT, UP, LEFT].cycle.each do |dir|
      yield dir
    end
  end
end

class StepGenerator
  include Enumerable
  
  def initialize(pivot)
    @pivot = pivot
  end

  def each
    return enum_for unless block_given?
    dg = DirectionGenerator.new.enum_for(:each)
    1.upto(@pivot + 1) do |n|
      next_dir = dg.next
      n.times do
        yield next_dir
      end
    end
    reverse_dg = DirectionGenerator.new.enum_for(:reverse_each)
    
    next_dir = reverse_dg.next
    @pivot.times do
      yield next_dir
    end
    
    (@pivot + 1).downto(1) do |n|
      next_dir = reverse_dg.next
      n.times do
        yield next_dir
      end
    end
  end
end

class RamenBoard
  def initialize(n)
    pivot = n * 4 
    @step_generator = StepGenerator.new(pivot)
    @board = Array.new(pivot + 1 ) { Array.new(pivot * 2 + 2, ' ') }
    @init_row = pivot / 2
    @init_col = @init_row
  end
  
  def fill_ramen
    @board[@init_row][@init_col] = "#"
    @step_generator.inject([@init_row, @init_col]) do |acc, (delta_r, delta_c)|
      r, c = acc
      @board[r + delta_r][c + delta_c] = "#"
      [r + delta_r, c + delta_c]
    end
    self
  end
  
  def to_s
    @board.map(&:join)
  end
  
end

1.upto(100) do |n|
  puts "n = #{n}"
  puts RamenBoard.new(n).fill_ramen.to_s
  puts
end