##### Question Design and implement an object-oriented system for tracking food-delivery driver payments with: 1) add_driver(driver_id, usd_hourly_rate); 2) record_delivery(driver_id, start_time, end_time) using a time format offering ≥1-second precision (deliveries ≤3 h, recorded post-completion); 3) get_total_cost(); then extend with: 4) pay_up_to(pay_time) to mark deliveries paid up to the given Unix epoch time; and 5) get_total_cost_unpaid(). Discuss storage choices, assumptions, OOP practices, and any deviations from production.

This question evaluates object-oriented API design, time-based state management, monetary calculation, and data modeling competencies in the System Design domain.

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Design delivery driver payment tracker | Rippling Interview Question

Food-Delivery Driver Payments System

Context

You are designing a small, object-oriented component to track and pay food-delivery drivers based on their hourly rate and completed delivery durations. Deliveries are recorded only after completion and never exceed 3 hours.

Assume all times are UTC and recorded with at least 1-second precision using Unix epoch time.

Requirements

Implement an object-oriented API with the following methods:

add_driver(driver_id, usd_hourly_rate)
- Registers a driver and their current hourly rate in USD.
record_delivery(driver_id, start_time, end_time)
- Records a completed delivery for the driver.
- Time format must support ≥1-second precision.
- Each delivery duration ≤ 3 hours.
- Deliveries are recorded only after completion (end_time ≤ now).
get_total_cost()
- Returns the total cost of all deliveries (paid and unpaid).

Then extend the system with:

pay_up_to(pay_time)
- Marks deliveries as paid if their end_time ≤ pay_time (Unix epoch time).
get_total_cost_unpaid()
- Returns the total cost of all unpaid deliveries.

Discussion Prompts

Storage choices (in-memory vs. persistent), data modeling, and indexing.
Assumptions (time zone, precision, rate changes, rounding).
OOP practices (entities, services, repositories, immutability, interfaces).
Any sensible deviations from production for an interview-quality solution.

Context

Assume all times are UTC and recorded with at least 1-second precision using Unix epoch time.

Requirements

Implement an object-oriented API with the following methods:

add_driver(driver_id, usd_hourly_rate)

Registers a driver and their current hourly rate in USD.

record_delivery(driver_id, start_time, end_time)

Records a completed delivery for the driver.
Time format must support ≥1-second precision.
Each delivery duration ≤ 3 hours.
Deliveries are recorded only after completion (end_time ≤ now).

get_total_cost()

Returns the total cost of all deliveries (paid and unpaid).

Then extend the system with:

pay_up_to(pay_time)

Marks deliveries as paid if their end_time ≤ pay_time (Unix epoch time).

get_total_cost_unpaid()

Returns the total cost of all unpaid deliveries.

Design delivery driver payment tracker

Quick Overview

Food-Delivery Driver Payments System

Context

Requirements

Discussion Prompts

Solution

Submit Your Answer

Design delivery driver payment tracker

Quick Overview

Food-Delivery Driver Payments System

Context

Requirements

Discussion Prompts

Solution

Submit Your Answer