Maze solving

Maze solving
You are encouraged to solve this task according to the task description, using any language you may know.

For a maze generated by this task, write a function that finds (and displays) the shortest path between two cells. Note that because these mazes are generated by the Depth-first search algorithm, they contain no circular paths, and a simple depth-first tree search can be used.

PicoLisp

<lang PicoLisp>(de shortestPath (This Goal Maze)

  (let (Path NIL  Best NIL)
     (recur (This Path)
        (when (and This (not (: mark)))
           (push 'Path This)
           (if (== Goal This)
              (unless (and Best (>= (length Path) (length Best)))
                 (setq Best Path) )
              (=: mark T)
              (recurse (: west) Path)
              (recurse (: east) Path)
              (recurse (: south) Path)
              (recurse (: north) Path)
              (=: mark NIL) ) ) )
     (disp Maze 0
        '((This) (if (memq This Best) " # " "   ")) ) ) )</lang>

Using the maze produced in Maze generation#PicoLisp, this finds the shortest path from the top-left cell 'a12' to the bottom-righ exit 'p1':

: (shortestPath 'a8 'k1 (maze 11 8))
   +   +---+---+---+---+---+---+---+---+---+---+
 8 | #   #   # | #   # |                       |
   +   +   +   +   +   +   +---+   +---+---+   +
 7 |   |   | #   # | # |   |       |       |   |
   +---+   +---+---+   +   +   +---+   +   +   +
 6 |   |       |     # |   |           |   |   |
   +   +---+   +---+   +---+---+---+   +   +---+
 5 |       |       | #   #   #   # |   |       |
   +---+   +---+   +---+---+---+   +---+---+   +
 4 |   |       |       |       | # | #   #   # |
   +   +---+   +---+   +---+   +   +   +---+   +
 3 |       |       |   |       | # | #   # | # |
   +   +---+---+   +   +   +   +   +---+   +   +
 2 |       |       |   |   |   | # | #   # | # |
   +   +   +   +---+   +   +---+   +   +---+   +
 1 |   |               |         #   # |     #
   +---+---+---+---+---+---+---+---+---+---+---+
     a   b   c   d   e   f   g   h   i   j   k