Knew it was some kind of interval problem but fumbled around for a minute before landing on a difference array approach.
Treat each trip as an interval of passenger count change: add passengers at pickup and subtract at dropoff. Use a difference map to accumulate net changes at each location, then sweep through locations in sorted order to check if the running total ever exceeds capacity.
Pro tip: Clarify whether trips can overlap and whether dropoffs can occur before pickups at the same location; handling these edge cases shows attention to detail and prevents off-by-one errors.
Ask about trip overlap, same location pickups/dropoffs, and whether capacity is inclusive. Confirm input format and expected output.
Represent each trip as two events: +passenger_count at pickup and -passenger_count at dropoff. Use a hash map to aggregate net changes per location.
Sort the unique locations and iterate, maintaining a running sum of passengers. After each location's net change, check if the sum exceeds capacity.
If the sum never exceeds capacity, return true; otherwise false. Analyze time O(n log n) due to sorting and space O(n) for the map.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.