Four fives: Method A

rot90a.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

class Rot90a
  def initialize
    @field_s = <<EOS
  1*  
  **  
1*1*1*
******
  1*  
  **  
EOS
    init_field
  end

  def start
    print_field
    # xy_rot90_test
    puts
    rotate_superpose("1", "2")
    rotate_superpose("2", "3")
    rotate_superpose("3", "4")
    print_field
  end

  def init_field
    @field = []
    @width = 0
    @height = 0
    s = @field_s.split(/\n/)
    s.each do |line|
      t = line.split(//)
      @field << t
      @width = [@width, t.length].max
      @height += 1
    end
    @x_center = (@width - 1) * 0.5
    @y_center = (@height - 1) * 0.5
  end

  def print_field
    print *(@field.map {|line_a| line_a.join + "\n"})
  end

  def xy_rot90(x_from, y_from)
    x1 = x_from - @x_center
    y1 = y_from - @y_center
    x2 = y1
    y2 = -x1
    x_to = (x2 + @x_center).to_i
    y_to = (y2 + @y_center).to_i
    [x_to, y_to]
  end

  def rotate_superpose(c_from, c_to)
    @height.times do |y|
      @width.times do |x|
        if @field[y][x] == c_from
          x_to, y_to = xy_rot90(x, y)
          @field[y_to][x_to] = c_to
        end
      end
    end
  end

  def xy_rot90_test
    @height.times do |y|
      @width.times do |x|
        x_to, y_to = xy_rot90(x, y)
        puts "(#{x},#{y}) => (#{x_to},#{y_to})"
      end
    end
  end
end

if __FILE__ == $0
  Rot90a.new.start
end