It's an Euclidean distance on a 2D plane, so the distance $ |DF| = \sqrt{2} $

Is the distance measures through orthogonal movements only, or are diagonal movements allowed?
For your example: Is the distance between D and F 1 or is it 2?

Thanks @Madjosz, now i know.

Is there anyway to see the solution to this Kata without solving it?
Don't have a 'Unlock Solution' Button for unkown reasons.

Tried to solve it with recurssion.
Could not get past the timeouts.

I assume the main lesseon learned is, that recurssion is slow in python.

Dunno, personally i prefere to handle tests for preconditions and assumptions on parameters (valid values) transparently and seperately