## CheckIO: Open Labyrinth

```class Node(object):
def __init__(self, index, crd):
self.index = index
self.crd = crd

def __sub__(self, other):
return (
self.crd[0] - other.crd[0],
self.crd[1] - other.crd[1]
)

def map_to_graph(maze_map):
graph = []

def get_index(crd):
for n in graph:
if n.crd == crd:
return graph.index(n)

index = 0
for x, row in enumerate(maze_map):
for y, v in enumerate(row):
if not v:
graph.append(Node(index, (x, y)))
index += 1

for node in graph:
n = node.index
x, y = node.crd
if x and not maze_map[x - 1][y]:
if x < len(row) - 1 and not maze_map[x + 1][y]:
if y and not maze_map[x][y - 1]:
if y < len(maze_map) - 1 and not maze_map[x][y + 1]:
return graph

def search(graph, n, route, reached):
GOAL = (9, 9)
DIRECTION = {(1, 0): "S", (-1, 0): "N", (0, -1): "W", (0, 1): "E"}
node = graph[n]
reached.append(n)
if node.crd == GOAL:
return ''.join(route)
for n in filter(lambda x: False if x in reached else True, node.links):
route.append(DIRECTION[graph[n] - node])
result = search(graph, n, route, reached)
if result: return result
route.pop()
return False

def checkio(maze_map):
trim = lambda L: [x[1:len(L) - 1] for i, x in enumerate(L) if 0 < i < len(L) - 1]
graph = map_to_graph(trim(maze_map))
return search(graph, 0, [], [])  # depth-first search

if __name__ == '__main__':
#This code using only for self-checking and not necessary for auto-testing
def check_route(func, labyrinth):
MOVE = {"S": (1, 0), "N": (-1, 0), "W": (0, -1), "E": (0, 1)}
#copy maze
route = func([row[:] for row in labyrinth])
pos = (1, 1)
goal = (10, 10)
for i, d in enumerate(route):
move = MOVE.get(d, None)
if not move:
print("Wrong symbol in route")
return False
pos = pos[0] + move[0], pos[1] + move[1]
if pos == goal:
return True
if labyrinth[pos[0]][pos[1]] == 1:
print("Player in the pit")
return False
print("Player did not reach exit")
return False

# These assert are using only for self-testing as examples.
assert check_route(checkio, [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1],
[1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1],
[1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1],
[1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]), "First maze"
assert check_route(checkio, [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]), "Empty maze"
assert check_route(checkio, [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1],
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]), "Up and down maze"
assert check_route(checkio, [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1],
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]), "Dotted maze"
assert check_route(checkio, [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1],
[1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1],
[1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1],
[1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1],
[1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1],
[1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]), "Need left maze"
print("The local tests are done.")```

https://www.checkio.org/mission/open-labyrinth/