Good question!
No. The tricky test case should not be provided. The constraints are given and it is the responsibility of the solver to determine what cases need to be tested from that range. This is much more important than writing code.
If you get WA, your solution is WRONG. If you can prove that your method is correct on paper, then you have a code implementation error, but if you can't prove your solution on paper, then you have not solved the problem and should not yet be writing code.
The first step when you get a WA is the hardest but most important. Assume your solution is wrong!
If you need help, please continue to post, but I have confidence that you can do it.
