Doordash Interview Questions
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Design a donation service for a 3‑day charity
System Design Prompt You are designing an online donation service for a 3-day charity campaign. Requirements - Donors can: - Select a charity campai...
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 dasher pay with peak-hour query
Problem: Dasher pay calculation + peak-hour earnings You are given historical delivery records for a driver (“dasher”). Each record contains: - start_...
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: - ...
Debug and harden a driver-selection component
Debugging Exercise: “Pick Dasher” You are given a small codebase for selecting a dasher (driver) using a heap/priority-queue–like structure. The curre...
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...
Describe a conflict and how you resolved it
Behavioral Questions Answer the following using a clear structure (e.g., STAR: Situation, Task, Action, Result). 1. Tell me about a conflict you had w...
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 ...
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...
Design a 3-day online donation system
System Design: 3-day donation campaign Design an online donation system for a 3-day fundraising campaign. Requirements - Users can donate money to a c...
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...
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...
Analyze Spending Patterns and Restaurant Performance Using SQL/Python
orders +-------------+---------+---------------+---------------------+ | delivery_id | user_id | restaurant_id | order_date | +-------------+...
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...
Find longest common ordered restaurant list
You have two delivery drivers who each have a pickup plan represented as a list of restaurant IDs (strings). Because there is only one car, the combin...
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...
Diagnose and experiment to reduce late deliveries
Two-Sided Delivery Platform: Rising Late Deliveries You are the first analyst on a two‑sided delivery platform that handles both food and parcel order...
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...
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...