This company provides one of the worst interview experiences.

• The recruiter does not respond in a timely manner.
• The company does not give an overview of the interview process to candidates before it begins.
• If you ask for information, such as the LinkedIn profile of the interviewer, to help you prepare for the interview, the recruiter does not even bother responding to your email.
• If you are rejected, you will not receive feedback in a timely manner, nor will you find out the details.

Write a program to check whether a given tree is a binary search tree.

In a linked list, find the nth element from the end.

System design question: Design an alert processing system.

Implement a cache where each element has its own expiry time.