Practice/DoorDash/Design and implement Dasher payout calculation system

Design and implement Dasher payout calculation system

CodingMust

Problem

You are building a payment calculation system for a food delivery platform. Drivers pick up and deliver orders, and their earnings depend on two factors: a base rate per completed delivery and a bonus multiplier based on how many deliveries they were juggling at the time of completion.

Your task is to implement a function that processes a stream of delivery events for a single driver and calculates their total payout for a shift.

Each event contains:

• delivery_id: unique identifier for the delivery
• timestamp: when the event occurred (integer, monotonically increasing)
• status: one of "accepted" (driver picked up the order), "delivered" (driver completed the delivery), or "cancelled" (delivery was cancelled)

The payment rules are:

1. Drivers only get paid for deliveries with status "delivered"
2. The base payment per delivery is multiplied by a bonus factor
3. The bonus factor depends on how many deliveries the driver had "in flight" (accepted but not yet delivered/cancelled) at the moment they completed a delivery
4. Cancelled deliveries do not generate payment but do count toward concurrent delivery calculations while they were active

Requirements

1. Process events in chronological order (by timestamp)
2. Track which deliveries are currently active (accepted but not completed/cancelled)
3. When a delivery is marked "delivered", calculate payment as: base_rate * bonus_multipliers[concurrent_count]
4. Return the total payout across all completed deliveries
5. Assume all events are valid (every accepted delivery has a corresponding delivered/cancelled event)

Constraints

• 0 ≤ events.length ≤ 10,000
• Timestamps are unique and events are provided in sorted order
• 1 ≤ base_rate ≤ 100
• bonus_multipliers dict contains all necessary concurrent counts as keys
• All delivery_ids are unique strings
• Return value should be a float

Examples

Example 1:

` Input: events = [ {"delivery_id": "D1", "timestamp": 100, "status": "accepted"}, {"delivery_id": "D1", "timestamp": 200, "status": "delivered"} ] base_rate = 10.0 bonus_multipliers = {1: 1.0, 2: 1.5, 3: 2.0}

Output: 10.0

Explanation: Driver accepts D1 at t=100. At t=200 when D1 is delivered, there is 1 concurrent delivery (D1 itself), so payment is 10.0 * 1.0 = 10.0 `

Example 2:

` Input: events = [ {"delivery_id": "D1", "timestamp": 100, "status": "accepted"}, {"delivery_id": "D2", "timestamp": 150, "status": "accepted"}, {"delivery_id": "D1", "timestamp": 200, "status": "delivered"}, {"delivery_id": "D2", "timestamp": 250, "status": "delivered"} ] base_rate = 10.0 bonus_multipliers = {1: 1.0, 2: 1.5, 3: 2.0}

Output: 25.0

Explanation:

• At t=200 when D1 completes, there are 2 concurrent deliveries (D1, D2): 10 * 1.5 = 15
• At t=250 when D2 completes, there is 1 concurrent delivery (D2): 10 * 1.0 = 10
• Total: 15 + 10 = 25 `

Example 3:

` Input: events = [ {"delivery_id": "D1", "timestamp": 100, "status": "accepted"}, {"delivery_id": "D2", "timestamp": 110, "status": "accepted"}, {"delivery_id": "D3", "timestamp": 120, "status": "accepted"}, {"delivery_id": "D1", "timestamp": 130, "status": "delivered"}, {"delivery_id": "D2", "timestamp": 140, "status": "delivered"}, {"delivery_id": "D3", "timestamp": 150, "status": "delivered"} ] base_rate = 10.0 bonus_multipliers = {1: 1.0, 2: 1.5, 3: 2.0}

Output: 55.0

Explanation:

• At t=130 when D1 completes: 3 concurrent → 10 * 2.0 = 20
• At t=140 when D2 completes: 2 concurrent → 10 * 1.5 = 15
• At t=150 when D3 completes: 1 concurrent → 10 * 1.0 = 10
• Total: 55 `