Doordash Software Engineer Coding & Algorithms Interview Questions
Practice 53 real Coding & Algorithms interview questions for Software Engineer roles at Doordash.
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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...
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...
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...
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_...
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...
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...
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 ...
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 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...
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-...
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...
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...
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...
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_...
Debug using logs and allocate tasks
You inherit a service where unit tests pass locally, but production logs show intermittent errors. Without a debugger, outline a step-by-step debuggin...
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...
Compute Differences Between Catalog Trees
You are given two rooted catalog trees. Each node has a unique string key among its siblings and an associated value. Compare the two trees and return...
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...
Compute nearest dashmart distances for queries
You are given an m x n grid where each cell is one of: -1 for a wall (impassable), 0 for a dashmart (a store), and INF = 2^31 - 1 for an empty room. M...
Compute nearest courier for each customer
You are given two arrays: customers and dashers. Each customer i has coordinates (xi, yi). Each dasher j has coordinates (aj, bj) and an integer id. F...