DoorDash Coding & Algorithms Interview Questions
DoorDash Coding & Algorithms interview questions typically emphasize practical problem solving under time pressure, clear code, and product-minded tradeoffs. What’s distinctive is a bias toward realistic engineering tasks—scheduling, graph traversal, and array/string manipulation appear often—combined with an expectation that you communicate tradeoffs, test edge cases, and iterate quickly. Interviewers assess algorithmic thinking, correctness, complexity reasoning, and the ability to refactor or extend solutions when given follow-ups. Expect an initial technical screen followed by a loop of 2–4 interviews that blend live coding with behavioral and sometimes system-design conversations. For interview preparation, prioritize consistent timed practice on medium-to-hard problems, rehearse speaking your thought process, and run mock interviews in your target language and editor. Refresh core data structures, common patterns (DFS/BFS, two pointers, heaps, hash maps, dynamic programming), and time/space analysis. Finish prep by practicing end-to-end: state assumptions, outline an approach, code defensively, and validate with tests so you can both solve and clearly explain your solutions during the loop.

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Compute Nearest Destination Distances
You are given an m x n grid representing a city map. Each cell contains one of the following characters: - D: a destination - X: an obstacle - .: an o...
Compute Courier Delivery Pay
A delivery platform has a service that can return all orders delivered by a courier. You are given: - courierId: the courier's identifier. - ratePerMi...
Select the best dasher for an order
You need to assign an order to a dasher. Input: - An order with a pickup location (x, y). - A list of dashers, each with: - id - current location ...
Calculate Daily Driver Pay
You are given a one-day event log for a delivery driver. Each input record is a JSON event with fields such as order_id, event_type, timestamp, and ba...
Maximize Chef Assignment Profit
You are given three integer arrays: - chefSkill[i]: the skill level of the i-th chef. - dishDifficulty[j]: the difficulty level required to cook the j...
Minimize batches and allocate riders by time
Coding prompts (same interview round) 1) Minimum number of batches for time points You are given a list of event time points (integers), e.g. [1, 3, 5...
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...
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...
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: - ...
Can two names match with ≤2 swaps?
You are given two restaurant names represented as strings s and t of equal length (same character set, case-sensitive). In one operation, you may swap...
Find Each Cell's Nearest Source
Given an m x n grid containing 1 for source cells and 0 for regular cells, compute for every cell the shortest 4-directional distance to any source ce...
Implement a consistent hashing ring
Implement a class ConsistentHashRing that distributes keys across servers using a hash ring with virtual nodes. Required API: - ConsistentHashRing(rep...
Design dynamic connectivity with alive nodes
Design a data structure to maintain an undirected graph of N nodes, where each node has a boolean 'alive' flag. Support the following operations effic...
Count changed nodes between two menu trees
You maintain a merchant menu as a rooted tree. Each node represents a menu item/category and has: - key (string, unique among siblings) - value (integ...
Calculate Courier Earnings
Design a function to calculate total courier pay from a set of delivery orders. Assume time is represented as integer minutes, and intervals are half-...
Evaluate a Four-Operator Expression
Implement a function that evaluates an arithmetic expression string containing non-negative integers, optional spaces, and the operators +, -, *, and ...
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_...
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...
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 and refactor a legacy module
Given a legacy module named DasherPicker and a failing test suite, systematically debug and refactor the code while following a provided review checkl...