Compute Courier Delivery Pay
Company: DoorDash
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Technical Screen
A delivery platform has a service that can return all orders delivered by a courier.
You are given:
- `courierId`: the courier's identifier.
- `ratePerMinute`: the courier's pay rate.
- A service method such as `getOrders(courierId)` that returns a list of orders. Each order has:
- `startTime`: when the courier started working on that order.
- `endTime`: when the courier completed that order.
Assume times are represented as integer minutes and `endTime >= startTime`.
Implement a function to compute how much the courier should be paid.
Base requirement:
- Each order is paid independently.
- Total pay is the sum of `(endTime - startTime) * ratePerMinute` across all orders.
Follow-up:
- Couriers may handle multiple orders at the same time, so order intervals can overlap.
- Implement a second version that computes pay based on actual active working time, where overlapping intervals are counted only once.
- For example, if the courier has orders `[10, 20]` and `[15, 25]`, the active working time is `15` minutes, not `20` minutes.
Quick Answer: This question evaluates a candidate's ability to work with time-interval arithmetic, interval union/overlap reasoning, and aggregation of time-based pay, testing skills in algorithms and data handling for billing computations.