I had to go through two back-to-back interviews on campus.

In the first one, I think I excelled. In the second one, the interviewer cancelled my solution approach in a few seconds. I later checked and realized it would have led to a different, but correct, solution.

Then, the interviewer guided me through the solution, which I think I followed just fine and came to the correct answer.

My fear of being perceived as inadequate while being guided by the interviewer came true, and I didn't get the offer. Afterwards, they told me to improve my data structure and algorithm skills. At this point, I don't know how to improve those!

Given an expression with parentheses (possibly unmatched) and literals (letters, numbers) sprinkled in between, delete the minimum number of literals or parentheses to make the expression valid.