[Solved] build a perfect maze recursively in python

Question

The problem is that you’re not ensuring that the steps in your walk are valid.

The way you have it currently, walk could pick a neighboor that is out of the bounds of the maze. For example, if a maze is 5×5, attempting to access maze[5][?] or maze[?][5] will result in an IndexError like you get.

To fix this, you could define an is_valid method for your maze class, e.g.:

def is_valid(self, x, y):
    return (0 <= x < self.size) and (0 <= y < self.size)

Then, you when you pick a neighboor, you ensure it’s valid:

#...
else:
    new = choice(neighboor)
    while self.is_valid(new[0], new[1]) == False:
        new = choice(neighboor)

    while self.maze[new[0]][new[1]].getVisit():
#...

This snippet picks a neighboor, then, if it’s not valid, regenerates new until it finds a valid one.

But this loop would be better written as:

#...
else:
    while True:
        new = choice(neighboor)
        if self.is_valid(new[0], new[1]): break

    while self.maze[new[0]][new[1]].getVisit():
#...

There are more problems with your code, however, as you’ll eventually see, but this will get you past this specific one.

Accepted Answer