第12回オフラインリアルタイムどう書くの参考問題をRubyで解く

第12回オフラインリアルタイムどう書くの参考問題をRubyで解きました。
問題はこちらのリンクから。
http://qiita.com/Nabetani/items/1de39df381dfeee305ab

CHARS1=[
  ('A'..'K').to_a,
  ('L'..'V').to_a,
  ('W'..'Z').to_a+('a'..'g').to_a
]
CHARS2=[
  '52zwtqnkh'.split(''),
  '630xuroli'.split(''),
  '741yvspmj'.split('')
]

def make_map
  map = {}
  [CHARS1,CHARS2].each{|chars|
    chars.each_with_index{|row, i|
      row.each_with_index{|c, j|
        map[c] = []
        if j > 0
          nc = chars[i][j-1]
          map[nc][0] = c
          map[c][2] = nc
        end
        if i > 0
          nc = chars[i-1][j]
          map[nc][1] = c
          map[c][3] = nc
        end
      }
    }
  }
  3.times{|i|
    c = CHARS1[2][-1-i]
    nc = CHARS2[i][0]
    map[c][1] = nc+'L'
    map[nc][2] = c+'R'

    c = CHARS2[i][-1]
    nc = CHARS1[2][i]
    map[c][0] = nc+'L'
    map[nc][1] = c+'R'
  }
  map
end

def rotate(dir,c)
  if (c == 'L')
    dir -= 1
    dir = 3 if dir < 0
  else
    dir += 1
    dir = 0 if dir > 3
  end
  dir
end

def solve(q)
  map = make_map
  seq = "A"
  cur = "A"
  dir = 0
  q.chars.each{|c|
    move = c.to_i(16)
    if move == 0
      dir = rotate(dir,c)
    else
      move.times{
        cur = map[cur][dir]
        return seq + '?' if cur.nil?
        if cur.size > 1
          dir = rotate(dir, cur[1])
          cur = cur[0]
        end
        seq += cur
      }
    end
  }
  seq
end

DATA.readlines.each do |line|
  no,q,a = line.chop.split(/\s+/)
  ans = solve(q)
  print no + "\t" + ans
  puts ans == a ? ' o' : ' x'
end
__END__
0	2RcL3LL22	ABCNYjmpsvy147edcbcdef
1	L3R4L5RR5R3L5	A?
2	2ReLLe	ABCNYjmpsvy147eTITe741yvspmjYNC
3	1ReRRe	ABMXilorux036fUJUf630xuroliXMB