70th Yokohama.rb どう書く http://nabetani.sakura.ne.jp/yokohamarb/2016.07.ront/

hoge.rb

# とりあえず動けば良いバージョン

require "pry"
# U: 0, L: 1, R: 2, D: 3, Dead: 4

class Tile
  def initialize(table)
    @table = table
  end

  def from(i)
    @table[i]
  end
end

TILES = [
  tile1 = Tile.new({ 0 => 1, 1 => 0, 2 => 3, 3 => 2}),
  tile2 = Tile.new({ 0 => 2, 2 => 0, 1 => 3, 3 => 1}),
  tile3 = Tile.new({ 0 => 3, 3 => 0, 1 => 2, 2 => 1}),
  tile2 = Tile.new({ 0 => 4, 1 => 4, 2 => 4, 3 => 4}),
]
st = :a
PLACE_TO_CODE = [st]
15.times { PLACE_TO_CODE << st.succ; st = st.succ }

class Field
  def initialize(field_str)
    arr_field = field_str.split("/").map { |x| x.split(//) }

    @field = []
    arr_field.each_with_index do |line, h|
      @field[h] = []
      line.each_with_index do |x, w|
        @field[h][w] = TILES[x.to_i]
      end
    end
  end

  def solve(h, w, d)
    result = ""
    loop do
      break if h < 0
      break if w < 0
      break if h >= 4
      break if w >= 4
      result += PLACE_TO_CODE[h * 4 + w].to_s

      nd = @field[h][w].from(d)

      case nd
      when 0
        h -= 1
        d = 3
      when 1
        w -= 1
        d = 2
      when 2
        w += 1
        d = 1
      when 3
        h += 1
        d = 0
      when 4
        break
      end
    end

    result
  end
end

#f = Field.new("0113/1201/2201/2100")
#p f.solve(0, 1, 0)

def test(str, ans)
  f = Field.new(str)
  if f.solve(0, 1, 0) == ans
    warn "OK"
  else
    warn "NG"
  end
end

test( "0113/1201/2201/2100", "bcgfeabfjnoklpo" ) # 0    
test( "2110/2013/2210/0122", "bcgh" ) # 1    
test( "2222/2130/2121/2002", "bfg" ) # 2    
test( "0021/2212/2102/1220", "baeimnoplhdcbfjkgfe" ) # 3    
test( "0213/1221/0220/1103", "bfjnokgcbaefghlkjimn" ) # 4    
test( "3201/3120/3333/3333", "bfghdcgk" ) # 5    
test( "3233/3233/3133/3333", "bfjk" ) # 6    
test( "3333/3333/3333/3333", "b" ) # 7    
test( "1212/1201/2123/2220", "bfjkl" ) # 8    
test( "2212/3102/1002/2100", "bfgcba" ) # 9    
test( "0023/2221/1102/0031", "baeijnm" ) # 10    
test( "1121/3120/0212/1120", "bcdhgfba" ) # 11    
test( "2202/3211/2120/1210", "bfjklhgcd" ) # 12    
test( "3201/3211/1111/0100", "bfjkonjie" ) # 13    
test( "0121/1120/1111/1211", "bcdhgfbaefjkop" ) # 14    
test( "1212/1213/2103/0213", "bfjkgfea" ) # 15    
test( "1121/2212/1323/3031", "bcdhl" ) # 16    
test( "0030/1230/1121/0031", "baefg" ) # 17    
test( "2223/1211/0002/1200", "bfjimnokl" ) # 18    
test( "3210/0033/0201/0130", "bfei" ) # 19    
test( "0213/2220/0021/3002", "bfjim" ) # 20    
test( "2121/2112/1110/1010", "bcdhlkgfba" ) # 21    
test( "0113/1003/2303/2220", "bcgfj" ) # 22    
test( "2202/1110/1302/0313", "bfgkj" ) # 23    
test( "1211/3202/2102/0222", "bfjkgh" ) # 24    
test( "3113/0002/0112/1022", "bcgfjko" ) # 25    
test( "1200/3000/0121/0121", "bfe" ) # 26    
test( "2221/1122/1031/2200", "bfgh" ) # 27    
test( "1202/0121/0222/1300", "bfghlpo" ) # 28    
test( "0002/1012/1021/3300", "baefbc" ) # 29    
test( "0211/1200/2220/2103", "bfjnokghdc" ) # 30