/
-S-
/

0 0 0 0
    0 + 0 + 0
   0 0 0 + + 0
  0 + 0 + 0 + 0
 0 0 + + 0 0 + 0
0 0 + 0 + 0 0 + 0
 E 0 + 0 0 + + 0
  + + 0 + 0 + 0
   0 0 0 0 0 +
    + 0 + + +
     0 S 0 0

>>>RFRFFLFLFRFFLFFFLFLFFRFLFLFRFRFRF

  + 0 0 0 0 0 0
 0 0 0 0 0 + + 0
0 0 E 0 + 0 0 + 0
 0 0 0 0 0 0 0 +
  0 + 0 0 + + +
   0 0 + + 0 0
    S + 0 0 0

>>>Invalid maze!

0 E S

>>>LF


 E + 0
0 + + +
 0 0 S
  + +

>>>FFLF

  E
 0 +
0 + +
 0 +
  S

>>>RFFLFF

 0 E + 0 0
0 + 0 0 + +
 + 0 + + + 0
  + 0 + 0 + 0
   + + + 0 S

>>>FFLFLFFRFRFFRFF

 E 0 + + 0
0 + 0 + + 0
 + + + 0 + 0
  + 0 0 0 0 0
   + + + + 0
    + 0 S 0

>>>FLFFRFFRFLF

z=zip;d=z((-1,1,-2,2,-1,1),(-1,-1,0,0,1,1));E=enumerate;D={};t=tuple;o=list;b=o.index
for y,i in E(M.split('n')):
 for x,j in E(o(i)):
  c=(x,y);D[c]=j
  if j=='S':s=c
  if j=='E':e=c
def P(s,e,D,p):
 p=o(p);p.append(s);D=D.copy();D[s]=''
 for i in d:
  c=t(x+y for x,y in z(s,i))
  if c not in p and c in D:
   if D[c]=='E':L.append(p+[c])
   if D[c]=='+':P(c,e,D,p)
def R(p):
 a=[0,1,3,5,4,2];h=d[0];x=p[0];s=''
 for c in p[1:]:
  r=t(x-y for x,y in z(c,x));n=0
  while h!=r:n+=1;h=d[a[(b(a,b(d,h))+1)%6]]
  s+=['L'*(6-n),'R'*n][n<3]+'F';x=t(x+y for x,y in z(x,h))
 return s
L=[];P(s,e,D,[])
try:l=len(min(L))
except ValueError:print"Invalid maze!"
else:print min([R(i)for i in L if len(i)==l],key=len)

maze = """
     0 0 0 0
    0 + 0 + 0
   0 0 0 + + 0
  0 + 0 + 0 + 0
 0 0 + + 0 0 + 0
0 0 + 0 + 0 0 + 0
 E 0 + 0 0 + + 0
  + + 0 + 0 + 0
   0 0 0 0 0 +
    + 0 + + +
     0 S 0 0
     """
directions = [(-1, -1), (1, -1),
              (-2, 0), (2, 0),
              (-1, 1), (1, 1)]


maze_dict = {}
maze_lines = maze.split('n')
for y, row in enumerate(maze_lines):
    if row:
        for x, item in enumerate(list(row)):
            coordinates = (x, y)
            maze_dict[coordinates] = item
            if item == 'S':
                start = coordinates
            elif item == 'E':
                end = coordinates

list_of_paths = []


def find_path(start, end, maze_dict, current_path=None):
    if current_path is None:
        current_path = []
    current_path = list(current_path)
    current_path.append(start)
    current_dict = maze_dict.copy()
    current_dict[start] = '0'

    for direction in directions:
        new_coordinate = (start[0] + direction[0], start[1] + direction[1])

        if new_coordinate in current_path:
            pass

        elif new_coordinate in current_dict:
            if current_dict[new_coordinate] == 'E':
                list_of_paths.append(current_path + [new_coordinate])
                break
            elif current_dict[new_coordinate] == '+':
                find_path(new_coordinate, end, current_dict, current_path)


find_path(start, end, maze_dict)


def find_route(path):

    heading_R = [0, 1, 3, 5, 4, 2]
    heading = (-1, -1)
    current_pos = path[0]
    current_heading = directions.index(heading)
    output_string = []
    for coordinate in path[1:]:
        required_heading = (coordinate[0] - current_pos[0], coordinate[1] - current_pos[1])

        count_R = 0
        while heading != required_heading:
            count_R += 1
            heading_index = directions.index(heading)
            heading_order = (heading_R.index(heading_index) + 1) % len(heading_R)
            heading = directions[heading_R[heading_order]]

        if count_R:
            if count_R > 3:
                output_string += ['L'] * (6 - count_R)
            else:
                output_string += ['R'] * count_R

        output_string.append('F')
        current_pos = (current_pos[0] + heading[0], current_pos[1] + heading[1])
    return ''.join(output_string)


routes = []
try:
    min_len = len(min(list_of_paths))
except ValueError:
    print "Invalid maze!"
else:
    for i in list_of_paths:
        if len(i) == min_len:
            routes.append(find_route(i))

    print 'Shortest route to end: {}'.format(min(routes, key=len))