The core idea clicked fast: scan right to left, track the running max, any building taller than the current max makes the cut.
Start by clarifying the problem and edge cases, then propose an O(n) solution using a right-to-left scan while tracking the maximum height seen so far. After implementing, discuss variations like leftward views and non-strict comparisons, explaining how the algorithm adapts.
Pro tip: Emphasize that the right-to-left scan is optimal because it processes each building once, and mention that the same pattern applies to many 'next greater element' problems. Also, proactively discuss trade-offs between strict and non-strict comparisons to show depth.
Ask clarifying questions about input constraints, whether heights can be equal, and if the output should be sorted. Confirm that a building can see the ocean if no strictly taller building exists to its right.
Explain a right-to-left scan: initialize max_height to -infinity and an empty list. Iterate from the last building to the first, and if the current height is greater than max_height, add its index to the list and update max_height.
Write clean code for the algorithm, then walk through a small example to verify correctness. Mention that the list will be in decreasing order of indices, so reverse it to get increasing order.
State that the time complexity is O(n) because each building is visited once, and space complexity is O(k) where k is the number of visible buildings (or O(1) extra space excluding output).
Explain how to adapt the algorithm for leftward views (scan left-to-right) and for non-strict comparisons (use >= instead of >). Discuss implications, such as equal-height buildings seeing the ocean in non-strict mode.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.