You can merely solve the kata another time clicking the "train again" button; that won't cancel your previous submission, both will be visibile, but you could comment the second accordingly.

Is there a way to replace/update my previous submission? It works but I optimized it after submission, made it ~20 times faster, and it would be nice if I could publish the current, optimized version.

Hi, the input is an n x n matrix, as the description specifies, eg. it can be 321x321 not just 3x3.

I just started using the site and loved this one. Thank you.