After contests are over, I do look at solutions of other coders and try understand and and improve solutions for lower time… Can I be warned / banned in this case ?
No, there is no penalty for submitting someone else’s code in practice problems. Practice problems are like a sandbox for us to play with and learn programming. As far as I know, you are free to do anything. Be in paste someone else’s code to check how it works, tweak it and see how it performs, or even try various edge cases to break the test data for a problem. All are valid uses of practice problems.
In fact, these are encouraged here so we learn more about a problem. Not just viewing, but editing, copying, resubmitting and sharing someone else’s code can help you see a problem from someone else’s perspective. And when you do, feel free to share your approach with us so we can also learn.
All the best. And warm regards,