shortest path finder algorithm (python)

#(0: clear step), (5 or any number other than zero: obstacles)
state = [[0,0,0,0,0],
	 [0,5,5,5,0],
	 [0,5,5,5,0],
	 [0,5,5,5,0],
	 [0,0,0,0,0]]

def access(state, x, y):
	try:return state[x][y]
	except:pass

neighbours = lambda x, state,  player:list(filter(lambda x:x is not False,map(lambda x:x if 0<=x[0]<=len(state[0])-1 and x[1]>=0 and access(state, x[0], x[1]) == player else False, ((x[0]-1, x[1]),(x[0]+1, x[1]),(x[0],x[1]+1),(x[0],x[1]-1)))))

def finder(state, start, end, trac=[], paths=[], depth=0):
	if start == end:return True
	for row, col in set(neighbours(start, state, 0))-{start}:
		depth += 1
		state[row][col] = 5
		trac.append(start)
		if finder(state, start=(row, col), end=end, depth=depth) == True:paths.append(trac[::]+[(3,3)])
		state[row][col] = 0
		trac.remove(start)
		depth -= 1
	if depth == 0:
		minimum = len(min(paths, key=len))
		paths = [i for i in paths if len(i)==minimum]
		return paths

if __name__ == "__main__":
	for i in finder(state, (0,0), (4,4)):
		print(i)