Telephonic Interview - 2 interviewers, 2 basic algorithm questions on strings.

I answered both questions in time. They wanted me to improve the time complexity on the second question. Mine was O(n) time and O(1) space, since I had data insertion in hand. Then, I discussed a better approach and half-coded it, but there wasn't enough time to finish coding.

According to me, I did really well.

These interviewers are totally unpredictable and naive. Two freshers are testing any level of experienced candidates. They just have one solution in mind. If you approach it differently, they consider it incorrect.

They expect you to complete two questions perfectly in the best way (according to them), while ensuring the code is readable, maintainable, logical, and so on.

Parenthesis Validation

Input: string