Four interviews were scheduled over the phone across five days. These were conducted by different developers and test engineers.

The initial plan was to complete all four interviews in four days, but this was later rescheduled due to the non-availability of interviewers.

Here is the list of questions I can recall:

1. Find all palindromes in a string, considering all cases. If possible, use Collections.
2. Sort a stack (implemented using an array) optimally.
3. Find the number of 0s and 1s in an array containing only 0s and 1s.
4. Sort an array containing 0s, 1s, and 2s.
5. Explain the architecture of a Selenium-based automation framework.
6. How to test multiple WSDLs? What test cases or testing methods can be applied?
7. How to use multi-threading concepts in your automation framework?
8. What are immutable classes?
9. How to implement a queue with synchronized collections? (Which collection can be used and why?)
10. Page Object Model vs. Page Factory Model.
11. Singleton Class and the concept of a private constructor.
12. How to handle the same object with different properties across different browsers in a Selenium-based automation framework?