The single-pass constraint is where I tripped up initially.
Start by clarifying the event schema, payment rules, and constraints (single pass, O(1) space). Then outline a state machine that tracks shift state and accumulates running totals (deliveries, miles, minutes) using only scalar variables, and finally compute the final payment with minimum guarantees applied at shift end.
Pro tip: Explicitly call out edge cases like missing shift end, out-of-order events, and zero deliveries, and explain how your design handles them without extra memory—this shows production readiness.
Ask about event types, timestamp format, payment formula details, minimum guarantees, and whether events are guaranteed ordered. Confirm the single-pass and O(1) space constraints.
Identify the minimal state needed: shift active flag, last event timestamp, and running totals for deliveries, miles, and minutes. Use only scalar variables.
For each event, update state and counters accordingly: on shift start, initialize; on pickup/dropoff, increment deliveries and accumulate distance/time; on shift end, finalize.
At shift end, calculate base pay + per-mile + per-minute, then apply minimum guarantees (e.g., per delivery, per hour) by taking the max of computed and guaranteed amounts.
Explain how the design handles out-of-order events, missing shift end, and zero deliveries. Mention that this approach is scalable and memory-efficient.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.