Pythonists, I challenge you to a game of Sokoban Golf!

soko.py

'''
Sokoban Golf by Aur Saraf

At line 145 you will find a very naive solution for level 1.
You can easily learn the API from it.

How few lines do you need for solutions to levels 1, 2, and 3?

Do not modify the game or the levels in any way. Just remove the
level 1 solution and uncomment the level 2 and level 3 boards,
and try to solve all three in as few characters as possible.

The challenge is intentionally on ALL THREE LEVELS TOGETHER. You
should be writing utility functions that help with more than one
level.

Good luck, and have fun!
'''
WALL = '#'
EMPTY = ' '
PLAYER = '@'
CRATE = '*'
EMPTY_DESTINATION = 'X'
CRATE_IN_DESTINATION = 'V'

EMPTY_SYMBOLS = (EMPTY, EMPTY_DESTINATION)
CRATE_SYMBOLS = (CRATE, CRATE_IN_DESTINATION)

DIRECTIONS = SOUTH, WEST, NORTH, EAST = 'SWNE'
_dirs = lambda values: dict(zip(DIRECTIONS, values))
DIRECTION_VECTOR = _dirs((
    (1, 0),
    (0, -1),
    (-1, 0),
    (0, 1),
))
LEFT = _dirs((DIRECTIONS[(i - 1) % 4] for i in xrange(4)))
RIGHT = _dirs((DIRECTIONS[(i + 1) % 4] for i in xrange(4)))

class QuietBoard(object):
    def __init__(self, level):
        self.board = [list(row) for row in level.splitlines()]
        self.crates_at_large = level.count(CRATE)
        self.player = self._player_position(self.board)
        self.orientation = SOUTH
        self.on_destination = False

    def _player_position(self, board):
        for i, row in enumerate(board):
            if PLAYER in row:
                return (i, row.index(PLAYER))
        assert False

    def __str__(self):
        return '\n'.join(''.join(row) for row in self.board) + '\n' + str(self.orientation)

    def is_win(self):
        return self.crates_at_large == 0

    def at(self, (row, column)):
        return self.board[row][column]

    def forward(self):
        in_front = self._in_front(self.player)
        if self._is_movable_crate(in_front):
            self._slide_crate(in_front)
        if self._is_empty(in_front):
            self._slide_player()

    def left(self):
        self.orientation = LEFT[self.orientation]

    def right(self):
        self.orientation = RIGHT[self.orientation]

    def _is_movable_crate(self, position):
        return self._is_crate(position) and self._is_empty(self._in_front(position))

    def _in_front(self, (row, column)):
        drow, dcolumn = DIRECTION_VECTOR[self.orientation]
        return row + drow, column + dcolumn

    def _is_empty(self, position):
        return self.at(position) in EMPTY_SYMBOLS

    def _is_crate(self, position):
        return self.at(position) in CRATE_SYMBOLS

    def _slide_crate(self, position):
        if self.at(position) == CRATE_IN_DESTINATION:
            empty = EMPTY_DESTINATION
            self.crates_at_large += 1
        else:
            empty = EMPTY
        self._put(empty, position)
        destination = self._in_front(position)
        if self.at(destination) == EMPTY_DESTINATION:
            crate = CRATE_IN_DESTINATION
            self.crates_at_large -= 1
        else:
            crate = CRATE
        self._put(crate, destination)

    def _slide_player(self):
        destination = self._in_front(self.player)
        empty = EMPTY_DESTINATION if self.on_destination else EMPTY
        self.on_destination = self.at(destination) == EMPTY_DESTINATION
        self._put(empty, self.player)
        self._put(PLAYER, destination)
        self.player = destination

    def _put(self, symbol, (row, column)):
        assert (symbol in EMPTY_SYMBOLS) != self._is_empty((row, column))
        self.board[row][column] = symbol

class Board(QuietBoard):
    def __init__(self, level):
        super(Board, self).__init__(level)
        print self
        print 'Start!'

    def forward(self):
        super(Board, self).forward()
        print self
        if self.is_win():
            print 'You beat this level!'
        print

LEVEL0 = '''\
#############
#@  *      X#
#############'''

b = QuietBoard(LEVEL0)
b.left()
for _ in range(10): b.forward()
assert b.is_win()

LEVEL1 = '''\
#############
#@         X#
# ##*########
#    ########
#############'''
b = Board(LEVEL1)
b.forward()
b.forward()
b.left()
b.forward()
b.forward()
b.forward()
b.left()
b.forward()

b.left()
b.left()

b.forward()
b.right()
b.forward()
b.forward()
b.forward()
b.right()
b.forward()
b.forward()
b.right()

for _ in range(9): b.forward()

LEVEL2 = '''\
#############
#   ######  #
#@          #
##*#*# ####X#
##     ####X#
#############'''
#b = Board(LEVEL2)

# Mini Cosmos 01 (c) Aymeric Du Peloux
LEVEL3 = '''\
  ##### 
###   # 
# * # ##
# #  X #
#    # #
## #   #
 #@  ###
 #####  '''
#b = Board(LEVEL3)