I made a small update to the Python version so that an incorrect solution will terminate execution of any further tests. If this doesn't help, you may need to verify that your code isn't running an infinite loop. If you're not using a text editor/IDE, I'd recommend using one.

In Python...
What I get in the console is the following:
Errors: 1
STDERR:
Process was terminated. It took longer than 12000ms to complete
Why did my code time out? [...]

There's no further output. Also if I insert some print statements, nothing is written on the console if the process times out.

Prior to the "process terminated" message, there should be some kind of feedback printed to the console. Are you attempting this in JS or Python?

How can I see how many tests I passed? I only get the message that the process was terminated... (I have the feeling I'm missing something obvious :-))
thanks !

You can get a better idea of how much of a performance improvement is required by looking at how many of the final tests pass. There are 15 random tests for each tier (3 x 3 to 10 x 10); in total 120 random tests.

If you are completing most of the tests within the 12000 ms limit, then perhaps look for optimizations here or there. If your solution isn't passing most of the tests, then you may need to rethink your approach.

My code is too slow. The sample tests complete in about 300ms. Is it meaningful to try to optimize the code, or should I rethink my solution completely ?