DoorDash Software Engineer Coding & Algorithms Interview Questions
Practice 61 real Coding & Algorithms interview questions for Software Engineer roles at DoorDash.
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Simulate Constant-Time Random Courier Selection
Simulate Constant-Time Random Courier Selection Problem Implement simulate_random_picker(operations, random_values). The picker maintains a changing s...
Find the Minimum Parenthesis Deletions and Their Positions
Problem Given a string containing only ( and ), remove the minimum number of characters needed to make the remaining string a valid parenthesis sequen...
Implement dasher active-time calculator
Implement a function that, given a dasherId, a local pay-period interval [startLocalDateTime, endLocalDateTime), and a list of order events of the for...
Track the First Unique Restaurant in a Stream
Problem Restaurant IDs arrive one at a time. Support two operations: - add(value): append one occurrence. - showFirstUnique(): return the earliest-arr...
Find the Minimum Delivery Processing Speed
Problem A delivery worker has hours whole hours to finish n orders. Order i has work[i] units. If the worker's integer processing speed is speed units...
Calculate Driver Payments
This question evaluates a candidate's ability to implement interval arithmetic and overlap computation, perform data deduplication and filtering, hand...
Implement consistent hashing ring
Implement consistent hashing ring Implement consistent hashing for routing keys to servers. Provide APIs addNode(nodeId, weight), removeNode(nodeId), ...
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...
Validate a Shopping Cart
This question evaluates the ability to implement robust input and business-rule validation for shopping-cart items, including data integrity checks, i...
Solve tree distance and design file system
Solve tree distance and design file system Given a binary tree, find the maximum distance between two 'alive' nodes, where 'alive' nodes are initially...
Implement Timeout Refund Workflow
This question evaluates skills in deterministic workflow design, idempotency and retry-safety for external payment integrations, state-transition corr...
Compute Nearest Destination Distances
This question evaluates graph and grid traversal concepts, specifically multi-source shortest-path computation on a grid and handling special-cell con...
Count changed nodes between two menu trees
This question evaluates algorithmic problem-solving with tree data structures, testing competencies in hierarchical diffing, node matching by sibling ...
Identify members lacking specialty coverage
Identify members lacking specialty coverage Oscar wants to ensure that every insurance member has adequate access to in-network healthcare providers w...
Implement a simple service with tests
Implement a simple service with tests You're given a short written specification for a small service class (no external dependencies). Implement the c...
Implement image carousel with comments and upvotes
Implement an image carousel that supports: 1) cycling forward/backward and autoplay with a configurable interval; 2) a per-image comment thread with c...
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: - ...
Compute dasher pay from order event logs
You are given a list of delivery-order event records for a single dasher. Each record contains: - order_id - event_type in {CREATED, ACCEPTED, PICKED_...
Design hierarchical path store with create/set/get/remove
Design a hierarchical key-value path store supporting four operations on UNIX-style absolute paths (e.g., "/a/b"). Implement: 1) create(path, value): ...
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...