第28回オフラインリアルタイムどう書くの問題をRubyで解く

問題は
http://nabetani.sakura.ne.jp/hena/ord28spirwa/

def solve(q)
  ds,days = q.split(':')
  n,e,s,w = ds.split(',').map(&:to_i)
  done = [[0,0]]
  n.times{|i| done << [0,i+1]}
  e.times{|i| done << [i+1,0]}
  s.times{|i| done << [0,-i-1]}
  w.times{|i| done << [-i-1,0]}
  x,y = 1,1
  done << [1,1]
  d = :E
  days.to_i.times{
    case d
    when :E
      x += 1
      d = :S unless done.include?([x,y-1])
      d = :N if done.include?([x+1,y])
    when :S
      y -= 1
      d = :W unless done.include?([x-1,y])
      d = :E if done.include?([x,y-1])
    when :W
      x -= 1
      d = :N unless done.include?([x,y+1])
      d = :S if done.include?([x-1,y])
    when :N
      y += 1
      d = :E unless done.include?([x+1,y])
      d = :W if done.include?([x,y+1])
    end  
    done << [x, y]
  }
  d.to_s
end

DATA.readlines.each do |line|
  no,q,a = line.strip.split(/\s+/)
  ans = solve(q)
  print no + "\t" + ans
  puts ans == a ? ' o' : ' x'
end
__END__
0	2,3,5,4:85	S	 
1	1,2,3,4:1	E	 
2	1,2,3,4:2	S	 
3	1,2,3,4:3	S	 
4	1,2,3,4:4	W	 
5	1,2,3,4:27	E	 
6	1,2,3,4:63	E	 
7	1,2,3,4:40	W	 
8	1,4,3,2:40	S	 
9	3,3,3,3:30	S	 
10	3,3,3,3:31	E	 
11	3,3,3,3:32	E	 
12	3,3,3,3:70	S	 
13	3,3,3,3:71	E	 
14	3,3,3,3:72	E	 
15	1,1,1,1:7	N	 
16	1,2,1,1:7	W	 
17	1,6,1,1:7	S	 
18	1,8,1,1:7	E	 
19	1,1,1,1:30	N	 
20	1,2,1,1:30	W	 
21	1,5,1,1:30	S	 
22	1,8,1,1:30	E	 
23	9,9,9,9:99	W	 
24	5,6,3,8:3	E	 
25	5,8,1,1:11	W	 
26	2,8,1,2:18	S	 
27	3,2,3,1:20	N	 
28	3,3,8,1:28	N	 
29	2,5,1,2:32	E	 
30	2,5,1,6:33	E	 
31	1,2,5,7:34	N	 
32	3,6,5,6:36	E	 
33	6,2,8,1:39	S	 
34	3,1,2,3:41	W	 
35	1,1,3,4:45	W	 
36	1,3,1,2:46	N	 
37	4,4,4,4:49	W	 
38	3,1,4,4:55	N	 
39	6,6,2,1:56	W	 
40	3,2,1,2:59	S	 
41	2,7,7,1:60	S	 
42	3,1,1,1:63	N	 
43	4,6,4,1:78	E	 
44	7,5,3,6:79	W	 
45	7,8,3,1:81	E	 
46	3,2,5,2:82	S	 
47	1,1,3,4:84	N	 
48	7,4,1,5:88	S	 
49	3,6,5,3:89	S	 
50	1,4,2,3:92	N	 
51	1,3,4,5:93	W	 
52	2,4,8,1:94	W	 
53	3,6,1,7:99	S