Hello Codeforces community!
I have a suggestion that I believe could improve the debugging experience on Codeforces, especially for those practicing problems.
Currently, when a submission fails, Codeforces only tells us which test case failed but does not specify which part of the test case caused the wrong answer. This makes debugging quite difficult, especially when a test case contains multiple queries or operations.
Suggestion It would be helpful if Codeforces could display the exact sub-part of the test case that causes the wrong answer instead of just showing the entire input. For example:
If a test case consists of multiple queries, indicate which specific query caused the failure. If the error happens at a specific index in an array, highlight that index. Maybe an optional "debug mode" could be enabled for practice problems to provide such insights. Possible Concerns I understand that revealing too much information might go against the competitive programming spirit, and implementing this in live contests might be impractical due to performance concerns. However, adding this feature for practice problems could significantly improve learning and debugging efficiency.
What do you all think? Would this be a useful feature? Looking forward to your thoughts!
This is an interesting idea! Debugging failed test cases can be frustrating, especially when dealing with large inputs or multiple queries. Having a feature that highlights the exact point of failure in practice mode would make learning more efficient. However, implementing this might be challenging because Codeforces' current system only verifies the final output, not intermediate steps.
One possible workaround could be allowing users to enable more detailed logs in "debug mode," where intermediate outputs or mismatches are shown for failed cases. This would help without revealing too much of the test case structure.
It would be great if the Codeforces team considers something like this for practice problems!"
Learn to debug without knowing the test case. It's an important skill to have in contests.
I agree. One way to help do that is by reading the constraints and what you can do within such constraints, in order to understand the possible edge cases that intentionally abuse certain parts of your code; elsewise, you should look at the solution and analyze what the solution's logic considered for it to pass and what your program's logic didn't.
it means no improvement
Use a diff checker if you really need to
Learning to find where your code fails on your own is a critical skill; most olympiads don't show you the test cases at all.