My first instinct was just to sort everything and iterate, which is basically right, but I fumbled the grouping step initially.
Group log entries by license plate, then sort each group by timestamp to reconstruct the sequence of checkpoints for each vehicle. Iterate through consecutive checkpoint pairs, compute the Euclidean distance using the helper function, and accumulate the toll (base fee $2 + $0.10 per unit distance) for each plate. Finally, return a map from plate to total toll.
Pro tip: Clarify edge cases upfront: what if a vehicle has only one checkpoint (no trips)? What if timestamps are equal? Also, mention that you'd validate the input format and handle missing coordinates gracefully, showing attention to production-quality code.
Ask about input size, whether timestamps are unique per vehicle, and how to handle vehicles with fewer than two checkpoints. Confirm the toll formula and that the helper function is reliable.
Use a hash map to group log entries by license plate. For each plate, sort the entries by timestamp to get the correct sequence of checkpoints.
For each consecutive pair of checkpoints, retrieve their coordinates via the helper function, compute the Euclidean distance, and calculate the segment cost as 2 + 0.10 * distance.
Sum the segment costs for each vehicle and store the total in a map from plate to toll. Return the map.
Discuss time complexity: O(N log N) due to sorting, where N is total entries. Mention that grouping and sorting can be done in one pass if entries are already sorted, or use a priority queue if needed.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.