I had a 45-minute technical phone interview. The interview included 5 minutes of introduction and 5 minutes of Q&A at the end. Overall, the interview experience was okay. However, it would have been better as a video call because it's sometimes difficult to catch the interviewer's emotional signals over the phone.

Write a Stack class with push() and pop() methods, ensuring the pop() method is implemented without using the built-in pop() functionality. The following question was to write a MinStack class, which includes a method to find the minimal value of the stack using only the push() and pop() methods.