This is like those LeetCode questions in job interviews, or the interviewer wants a complicated O(n) solution when the problem as stated would be better solved

This is like those LeetCode questions in job interviews, or the interviewer wants a complicated O(n) solution when the problem as stated would be better solved with a simple O(n^2) solution because the maximum problem size is tiny. It's a mind-reading game of which assumptions the professor/interviewer wants to keep solid which ones are open to change.