瞬き星 〜 第2回 ESM オフラインどう書く (2015/12/24) https://gist.github.com/mattsan/07674b095908fda117a0

star.rb

require 'rubygems'

class Node
  attr :name
  attr_accessor :color

  def initialize(name, color)
    @name = name
    @color = color
  end

  def toggle
    @color = @color == 'W' ? 'R' : 'W'
  end
end

class Star
  attr :nodes
  def initialize
    pairs = ('A'..'J').zip('WWWWWRRRRR'.chars)
    @nodes = pairs.map {|pair|
      Node.new(*pair)
    }

    @routes = [
      %w(A J I C),
      %w(A F G D),
      %w(B J F E),
      %w(B I H D),
      %w(C H G E)
    ]
  end

  def toggle(name)
    node = find_node(name)
    node.toggle
    target_routes = @routes.select {|r| r.include?(name) }

    target_routes.each {|route|
      toggle_route(node, route)
    }
  end

  def toggle_route(node, route)
    case route.index(node.name)
    when 0
      if find_node(route[3]).color == node.color && find_node(route[1]).color != node.color
        [1, 2].each do |index|
          find_node(route[index]).color = node.color
        end
      elsif find_node(route[2]).color == node.color
        find_node(route[1]).color = node.color
      end
    when 1
      if find_node(route[3]).color == node.color
        find_node(route[2]).color = node.color
      end
    when 2
      if find_node(route[0]).color == node.color
        find_node(route[1]).color = node.color
      end
    when 3
      if find_node(route[0]).color == node.color && find_node(route[2]).color != node.color
        [1, 2].each do |index|
          find_node(route[index]).color = node.color
        end
      elsif find_node(route[1]).color == node.color
        find_node(route[2]).color = node.color
      end
    end
  end

  def find_node(name)
    @nodes.find {|n| n.name == name }
  end
end

def setup
  Star.new
end

def resolve(input)
  star = setup

  input.chars.each do |name|
    star.toggle(name)
  end

  star.nodes.map(&:color).join
end

def test(input, expected)
  result = resolve(input)
  if result == expected
    print '.'
  else
    puts
    puts %Q[test("#{input}", "#{expected}") #=> got #{result}]
  end
end

test("A", "RWWWWRRRRR")
test("F", "WWWWWWWRRW")
test("J", "WWWWWWRRWW")
test("AA", "WWWWWWWRWW")
test("IC", "WWRWWRRRWW")
test("FC", "WWRWWWWRRW")
test("AE", "RWWWRRRRRR")
test("GJ", "WWWWWWWWWW")
test("CCB", "WRWWWRWWWR")
test("BEF", "WRWWRWWRRR")
test("JGD", "WWWRWWWWWW")
test("IHCC", "WWWWWRWWWW")
test("AIDD", "RWWWWRRWWR")
test("IJFA", "RWWWWWWWWW")
test("ABCDE", "RRRRRRRRRR")
test("ICEBA", "RRRWRRRRRR")
test("DAHHD", "RWWWWRWWWR")
test("GJIJC", "WWRWWWWWRR")
test("FGHIJ", "WWWWWWWWRR")
test("HJICGA", "RWRWWRRRRR")
test("IBCIGC", "WRWWWWWWWW")
test("BIJJJB", "WWWWWWRWWW")
test("DCBCHGD", "WRWWWWWRRW")
test("JEABDHD", "RRWWRRRWRR")
test("JHFADHE", "RWWRRRRRWW")
test("HDGGDBIB", "WWWWWWWWWW")
test("IIDIHCCG", "WWWRWRRWWW")
test("BBFBICIE", "WRRWRRRWWW")
test("HJHCFBJGG", "WRRWWWWRRW")
test("AJJIEAAII", "RWWWRWWWWR")
test("AIDHJFGAE", "WWWRRWWWWW")
test("FGBGHCBHJJ", "WWRWWWWRRW")
test("EFIGIGGHHJ", "WWWWRRRWWR")
test("HGAFDIFFFF", "RWWRWRRRRW")
test("AABBCCDDEE", "WWWWWWWWWW")
test("ABCDEFGHIJ", "RRRRRWWWWW")
test("FGHIJABCDE", "RRRRRRRRRR")

その後 test("BBFBICIE", "WRRWRRRWWW") 以外通るようになり、しばらくしたあとに全部通すことができました。