Doordash Interview Questions
Practice the exact questions companies are asking right now.
Compute courier pay and implement load balancing
Problem 1: Compute courier (delivery driver) pay You are given a sequence of delivery-related events for a courier during a day. Your task is to compu...
Design a donations service with 3-day rolling totals
Design a service that ingests donations and serves rolling 3-day donation totals. Requirements Core features 1. Ingest donation events: - Each dona...
Compute cart total with best promotion
Assume you are implementing a checkout price calculator for an online shopping cart. You are given: - A list of items in the cart. Each item has: - ...
Analyze Spending Patterns and Restaurant Performance Using SQL/Python
orders +-------------+---------+---------------+---------------------+ | delivery_id | user_id | restaurant_id | order_date | +-------------+...
Generate Weekly Revenue and Engagement Summary with Pandas
events | user_id | event_time | event_type | platform | revenue | |---------|---------------------|------------|----------|---------| | 101 ...
Investigate Causes of Cold Meal Deliveries
Investigate and Reduce Cold Food Deliveries Context You are a Data Scientist at a large food-delivery marketplace. Customer complaints about meals arr...
Design API that aggregates three downstream APIs
You are given three existing HTTP JSON APIs owned by other backend services: - Service A: GET /service-a?user_id={id} → returns basic user profile dat...
Design a resilient dasher payment system
System Design: End-to-End Payouts from Order Lifecycle Events You are designing a system that computes delivery driver (Dasher) payouts from an event ...
Write SQL for percent and window changes
Use PostgreSQL. Assume today = 2025-09-01. You must use CTEs and multiple window functions. Schema and tiny samples are below. Schema: - exposures(uni...
Implement round-robin load balancer
Implement a load balancer that distributes incoming requests across N backend servers in strict round-robin order. Requirements: ( 1) Support addServe...
Experiment on increasing order notifications
Experiment Design: Increasing Order‑Related Push Notifications Context You are asked to design, measure, and make decisions about increasing order‑rel...
Evaluate Impact of Bicycle Deliveries on Efficiency and Costs
Scenario A food-delivery marketplace plans to let couriers (dashers) opt in to deliver by bicycle in addition to cars. Question State the primary busi...
Design a 3-day donation platform
Design: Online Donation Platform for 3‑Day Campaigns Context You are designing an online donation platform optimized for short, 3‑day fundraising camp...
Debug round-robin, DashMap, and simple cache
You are given a service that routes requests to a list of nodes, each marked as either available or unavailable. The pickNode() function is intended t...
Debug a driver assignment bug
Given a service that selects the best delivery driver ("dasher") for an order, users report incorrect assignments. With a provided codebase and failin...
Design and analyze a switchback experiment
Switchback Experiment Design: Reducing Cold-Food Incidents for Bike Couriers You are optimizing a delivery marketplace feature suspected to reduce col...
Implement and compare round-robin and consistent hashing
Implement a round-robin load balancer that selects among service nodes, skipping unavailable nodes and wrapping around correctly. Fix typical pitfalls...
Design cron scheduler and reward/review system
System Design: Company-Wide Scheduler Platform and Employee Review & Rewards System You are designing two platforms for a fast-growing, multi-tenant t...
Diagnose Causes of High Out-of-Stock Rate in Groceries
Product and Operations Case: Grocery OOS, Delivery Radius, and Free Delivery Context You are a data scientist in an onsite analytics and experimentati...
Write SQL for late-delivery metrics by window
You are given two tables. Assume PostgreSQL. Define delivery duration as delivered_at − pickup_time (exclude rows with null pickup_time or delivered_a...