+9Design a rate limiterSystem designDesign a service that limits how many requests each API client can make. It sits in front of every API endpoint at high traffic.
Reported by 1 member · Last asked Oct 2026
Questions
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Disagreements with a coworker, another team and a menteeBehavioralThree behavioral questions in one round, each answered with a real story: what happened, what you did and how it ended. 1. You and a coworker disagreed about the work. How did you…Last asked Oct 2026- +1URL router with single-segment wildcardsCodingBuild a small URL router. - A pattern and a path are split on / into segments. Empty segments are ignored, so /a/b/ is the same as /a/b, and / is the empty path. - A pattern…Last asked Oct 2026
Key-value cache with per-entry TTLCodingImplement an in-memory key-value cache where every write gives a key, a value and a time-to-live. Once an entry's time is up it must behave as if it was never written. Support…Last asked Oct 2026- Fix planted bugs in an open-source library from its failing testsCodingYou get a checkout of a real open-source library (a template engine, an HTTP client or a parser) with a few bugs planted in it. Run the test suite, follow the failures into code…Last asked Oct 2026
Game of Life on a grid too big for memoryCodingStarting from working Game of Life code, adapt it to a grid stored on disk that cannot be loaded at once, using given file helpers. Keep next-generation semantics exact, including…Last asked Oct 2026
Fetch paginated records and filter them by rules and a historical averageCodingAn HTTP endpoint serves patients' medical records, ten per page, with no page count given up front. Each record has many fields, most of them irrelevant to you. 1. Fetch every…Last asked Oct 2026
Design a sandboxed cloud IDESystem designGive every user a browser-based editor with a terminal and a private container that runs their code, starts in seconds, isolates untrusted code, and saves their work.Last asked Oct 2026
Limit tree height by deleting nodesCodingYou are given a rooted N-ary tree. Every node has a unique integer id. The tree is passed as children: dictint, listint (a node with no entry has no children) together with the…Last asked Oct 2026- +7Design a distributed web crawlerSystem designCrawl billions of web pages politely and repeatedly, deduplicating URLs and content, to feed a search index or a training-data pipeline.Last asked Oct 2026
- Work queue with a dead-letter queue and dependency cycle detectionCodingBuild an in-memory work queue for pipeline tasks that depend on each other (download, then tokenize, then train). Workers call nextready() to take a task and report back with…Last asked Oct 2026
+4Mini spreadsheet with formulas and cycle detectionCodingBuild a mini spreadsheet with cell get and set, formula evaluation over dependencies, cached values with eager updates, and cycle detection. Covers the bank's spreadsheet variants…Last asked Oct 2026
Sorting complexity: beat O(n²), then design the worst correct sortCodingA verbal round with no coding, asked as a quick series: 1. Explain a sorting algorithm faster than O(n²) and why it is faster; be ready for quicksort's worst case. 2. Name or…Last asked Oct 2026- Make a charge-then-record payment flow safe against crashes and retriesCodingA backend first charges a customer through an external payment provider and then writes the payment to its own database. You are shown code like this (in Java or Python) and asked…Last asked Oct 2026
- Review a CSV-building function for correctness and performance bugsCodingYou are shown a short function (in Java or Python) that turns a table, a list of rows of string cells, into CSV text by appending to a string in a loop. Say what is wrong with its…Last asked Oct 2026
- Per-user chat event counts in a sliding windowCodingA chat service runs for months without restarting. It sends you a stream of message events. Each event has a userid, a chatid and an integer timestamp in seconds. You must answer…Last asked Oct 2026
- Design a real-time trivia battle royale with live spectatorsSystem designDesign a trivia battle royale. A room holds dozens to a hundred or more players. Questions go out round by round; after each round, players who answered wrong and the slowest…Last asked Oct 2026
- Split-tender payments with gift cards, surcharges and refundsCodingAt a retail point of sale one purchase can be paid with several methods, for example part on a gift card and the rest on a credit card (a split-tender transaction). Write the code…Last asked Oct 2026
Detect security attacks in text logsCodingScan text logs for patterns indicating security attacks and report the offending entries. Reported on 1point3acres' Fireworks AI bank; reconstructed in our own words.Last asked Oct 2026
+23Project deep dive: present a project you ledBehavioralPresent a project you led in about 20 minutes: context, your role, the architecture, three hard trade-offs, metrics, cost and return, and what you would change. Then take 25…Last asked Oct 2026- Persistent key-value store with binary snapshotsCodingImplement an in-memory key-value store whose whole state can be saved to, and restored from, a storage medium that holds a single binary blob. You are given: ImplementLast asked Oct 2026
Train a model to extract highlight snippets from textML designEach training example is a passage of text with the snippet that should be highlighted and its start and end positions. Complete a PyTorch training pipeline that learns to predict…Last asked Oct 2026- Merge two config trees with per-node merge rulesCodingTwo configuration files have been parsed from YAML into trees of dicts, lists and plain values: a base and an overlay. Merge the overlay into the base. Each node can carry its own…Last asked Oct 2026
- Best value from unit-weight items with limited copiesCodingA bag holds at most capacity units of weight. There are n kinds of item; every copy of kind i weighs 1 and is worth valuesi, and there are countsi copies of it. Return the most…Last asked Oct 2026
- Design a real-time multiplayer typing raceSystem designDesign an online typing race. Each race has 2 to 8 players. When the race starts, every player gets the same generated passage and types it; the first to finish the whole passage…Last asked Oct 2026
Minimum time to finish dependent steps run in parallelCodingA job is split into n steps numbered 0 to n - 1; step i takes durationsi minutes. A pair u, v in dependencies means step u must finish before step v starts. Any number of steps…Last asked Oct 2026- Find every recipe you can make from your suppliesCodingYou have an unlimited stock of some basic supplies and a book of recipes. Each recipe has a unique name and a list of ingredients; an ingredient can be a supply, the name of…Last asked Oct 2026
- AI-agent security detection over streaming telemetryAI system designDesign a system in which an AI agent reads a stream of security telemetry and runs detections on it. About 1 TB of data arrives per day. It was asked like a traditional system…Last asked Oct 2026
- Merge overlapping collinear segments in the planeCodingSegments in 2D each carry an ordered list of points. Merge segments that lie on the same line and overlap, keeping every point, and take care with vertical segments and…Last asked Oct 2026
- Ingest MCAP driving logs and query them by timestampCodingBuild a small data service over recorded vehicle drives, with an AI coding assistant allowed. Each drive (a run) is stored as an MCAP file: timestamped messages on several topics…Last asked Oct 2026
- Largest permutation after sorting one fixed-length windowCodingYou get a permutation of 1 to n and a window size w. Exactly once, choose a contiguous window of exactly w elements and sort the elements inside it. Return the lexicographically…Last asked Oct 2026
Is the store open? Hours with split shifts and overnight windowsCodingWrite a check that answers whether a store is open at a given moment, in Java. The schedule starts simple and gets richer step by step, and every earlier query must keep working…Last asked Oct 2026- Collect host metrics and post them to a serverCodingOn a Linux VM, gather CPU, memory and disk usage, send them as JSON in an HTTP POST to a given endpoint, and then flag any metric above a threshold.Last asked Oct 2026
- +5Behavioral round on company valuesBehavioralA behavioral round anchored on the company's published values: bring experiences covering conflict, feedback, mentorship, leading work and technical trade-offs. Reported on…Last asked Oct 2026
- +10Recruiter screen: motivation, background and logisticsBehavioralA short first call with a recruiter: a few standard behavioral questions about your background and why you want the role, then timeline, location and compensation expectations…Last asked Oct 2026
- +7ML fundamentals deep dive for ML rolesML designAfter a short walk through your resume, expect fast questions on machine learning basics, usually centred on your own area (language models, vision, recommendations). For each…Last asked Oct 2026
- +1Design a parking lotOO designModel a multi-floor parking lot with spot types for motorcycles, cars and trucks: park, unpark, find free spots, and charge by time.Last asked Oct 2026
+1Reachability in a time-indexed train scheduleCodingGiven train departures and arrivals with timestamps, decide whether a destination is reachable from a start station without time travel. Reported on 1point3acres' Glean bank;…Last asked Oct 2026- Microorganisms eating neighbours: the largest survivorCodingMicroorganisms stand in a row. Each one has a family (a letter) and a size (a positive integer). A microorganism can eat the neighbour directly to its left or right when that…Last asked Oct 2026
- Paint house: cheapest daily colors with no repeat on consecutive daysCodingFor the next n days a store sells blue, green and red shirts, and you get three cost arrays, one per color, giving each color's price on each day. You buy exactly one shirt every…Last asked Oct 2026
- Follow one-way links to the endpoint or the last node before a loopCodingA network has nodes joined by one-way links, and each node links to at most one other node. Starting from a given node, follow the links and return the endpoint: the last node the…Last asked Oct 2026
- Design LLM review summaries that resist prompt injection and PII leaksAI system designBuild a platform that takes customer product reviews from an online store and has a large language model summarize them for an internal dashboard. The round centered on trust and…Last asked Oct 2026
- Median of several sorted arraysCodingYou get several integer arrays, each sorted in non-decreasing order. Return the median of all their values taken together. The interview started with exactly two arrays and then…Last asked Oct 2026
Conversation history under a token budgetCodingFit a conversation history into a token budget for the next model call, keeping the most important messages and dropping or summarizing the rest. Reported on 1point3acres' Sierra…Last asked Oct 2026- Image transform pipeline with a wall-clock budgetCodingApply a fixed sequence of image transforms (grayscale, flip, scale, blur, rotate) to every image in a directory, then speed the batch up with threads or processes to hit a…Last asked Oct 2026
- +2Concurrent same-host web crawlerCodingImplement a web crawler that finds every page reachable from a start URL on the same host, and fetches pages concurrently. You are given a blocking helper: Write: python def…Last asked Oct 2026
- +1Design an AI prompt playgroundAI system designDesign a web workspace where developers write prompts, run them against several models and settings, compare outputs side by side, and save and share versions.Last asked Oct 2026
- Design a distributed AI model downloaderAI system designGet a new multi-hundred-gigabyte model checkpoint onto thousands of GPU hosts as fast as possible without overloading the storage it comes from.Last asked Oct 2026
- +2Memory allocator with malloc, free and coalescingCodingManage one arena of size bytes, addressed by offset from 0. You hand out and take back ranges of it, like malloc and free in C. Nothing is stored in the arena itself; track it in…Last asked Oct 2026
- Merchant onboarding CSV validatorCodingMerchants submit their business details as rows of a simple CSV. Before a merchant can accept payments, every row must pass a set of checks. Write validaterecords(data…Last asked Oct 2026
- Extensible chat app with command botsCodingImplement an in-memory chat app with one shared channel that people and bots post to. Users send text. Some messages are slash commands (/name arg ...), and bots can respond to…Last asked Oct 2026
Assign robots to their nearest pickup items on a grid with obstaclesCodingOn an m x n grid with obstacles there are k robots and k items. Send each robot to one item, preferring the item nearest to it by walking distance. Several robots can share the…Last asked Oct 2026- Check and insert among a million user IDsSystem designA service holds about a million user IDs. Each request carries a user ID: if it is not in the set yet, add it. Decide how to store the IDs and run this check-and-insert, and talk…Last asked Oct 2026
- Behavioral stories for the Leadership PrinciplesBehavioralEvery interview in the loop sets aside time for behavioral questions tied to the company's Leadership Principles. Expect asks like a deadline you nearly missed, a disagreement…Last asked Oct 2026
- +5Design a payment systemSystem designAccept card payments for merchants: authorize, capture, settle with card networks, and reconcile, never charging twice or losing money.Last asked Oct 2026
- One-on-one chat system with presence and offline queueSystem designDesign direct messaging for single-device users: delivery, presence, offline-recipient queueing, session storage, and the choice of message bus. Group chat is explicitly out of…Last asked Oct 2026
- +5Implement an LRU cacheCodingImplement a least-recently-used cache with get(key) and put(key, value), both in O(1) time, with a fixed capacity.Last asked Oct 2026
- Count ordered routes that visit one shop of each of four typesCodingYou need four things from four kinds of shop: a bookshop, a school-supply shop, a sports store and a stationery store. The town has many shops of each kind, joined by roads…Last asked Oct 2026
- +7How do you use AI in your work?BehavioralDescribe how AI tools fit into your engineering work: where they help, where they fail, how you verify their output, and how they have changed the way you or your team work.Last asked Oct 2026
- Build a transaction rule engine with an AI assistantCodingWith an AI coding assistant built into the editor, implement a rule engine that reads allow and block conditions and applies them to a list of transactions. You are graded on how…Last asked Oct 2026
- +1Find the planted bugs in a small Transformer training scriptCodingA small Transformer, its training script and some tests are provided, with a few bugs hidden in them. Find and fix them so the loss goes down and the outputs are correct, and…Last asked Oct 2026
- Walk through your career decisionsBehavioralExplain the main choices in your education and career: what alternatives you had, what constrained you, why you chose as you did, and how you judge those choices now. Connect them…Last asked Oct 2026
- +3In-memory file system with files and foldersCodingImplement an in-memory file system with path-based file and folder access, plus follow-ups on per-directory limits, duplicate names and identical contents. Covers the bank's vault…Last asked Oct 2026
- Tell me about a time you overcame a major obstacleBehavioralDescribe a time an unexpected obstacle threatened an important goal. Explain what the obstacle was, your role, the options you weighed, what you did, and how it turned out. Expect…Last asked Oct 2026
- +4Anthropic OA: leveled in-memory record storeCodingA timed, multi-level exercise building an in-memory store of records with fields: create and read first, then scans and filters, then timestamps with expiry, then backup and…Last asked Oct 2026
- Fault-tolerant work queue with leases and retriesCodingImplement an in-memory work queue that keeps working when workers crash. Workers take a task, process it, and report success or failure. A worker that dies silently must not lose…Last asked Oct 2026
- +1Number of islands as land is addedCodingA grid starts as all water. Positions are turned into land one at a time; after each addition, return the current number of islands (land cells connected up, down, left or right)…Last asked Oct 2026
- What do you do when two people disagree?BehavioralDescribe how you handle a disagreement between two people and support it with a concrete example from your own work. Show how you found what each side really cared about, how the…Last asked Oct 2026
- A leader who shaped you and how you used the lessonBehavioralDescribe a manager or tech leader who had a strong, lasting effect on you. Say what they actually did in specific moments, not just what they were like, and how you later used…Last asked Oct 2026
- How do you prioritize when you have too much work?BehavioralExplain how you decide what comes first when there is more work than time, and back it up with a real example. A convincing answer names what you dropped or pushed back and why…Last asked Oct 2026
- Maximum frequency stackCodingBuild a stack of integers with push(x) and pop(). pop removes and returns the value that occurs most often in the stack; when several values tie, it takes the one with an…Last asked Oct 2026
- Tell me about a time you improved things for a customerBehavioralDescribe a customer pain point you noticed and acted on, or a time you judged how good the customer experience really was. Explain how you learned what the customer needed, what…Last asked Oct 2026
- Build a driving-log replay viewer with an AI assistantCodingIn two to three hours, with an AI coding assistant, build a web app that loads recorded autonomous-vehicle logs from cloud storage and plays them back as an interactive…Last asked Oct 2026
- +1Lowest common manager in an org chartCodingA company's reporting structure is a rooted tree. Each person is an Employee with a unique name and a list reports of the people who report to them directly. The root is the CEO…Last asked Oct 2026
- +1Design a feature flag serviceSystem designLet teams turn features on for a percentage of users or specific accounts, with changes reaching every service within seconds and no per-request network call.Last asked Oct 2026
- Which area would you improve to do better work here?BehavioralIf you could get better at one thing right now, what would it be, and how would that improvement help your future work at Google? Pick a real gap rather than a strength in…Last asked Oct 2026
- Design an LLM agent for production status, work orders and quotesAI system designPeople at a manufacturing business talk to an AI agent in plain language. It has to handle three kinds of request: report how far along an order or production job is, open a new…Last asked Oct 2026
- +1Batched LLM inference API over GPUsAI system designDesign an inference API that batches requests across GPUs efficiently. The discussion goes deep on a few axes: utilization, scaling under spikes, and separating prompt processing…Last asked Oct 2026
Design an enterprise research agent with internal and web sources and citationsAI system designAn employee asks a hard research question. Design the assistant that answers it by searching both the company's own systems (documents, wikis, a CRM such as Salesforce) and the…Last asked Oct 2026- Concatenated wordsCodingGiven a list of distinct words, return every word that can be split into two or more pieces that are each a word in the list (the same word may be used more than once). A shorter…Last asked Oct 2026
- +6Design a metrics monitoring systemSystem designCollect metrics from every host and service, store them as time series, power dashboards over months of data, and alert when thresholds are crossed.Last asked Oct 2026
- Fewest moves for a chess piece to capture the kingCodingA rectangular board has blocked squares, your piece and the opposing king. Your piece's type decides the directions it may step in, and it can never move onto a blocked square…Last asked Oct 2026
- Fetch all pages until an empty batchCodingPage through a batched API until it returns an empty batch, collecting every record without fetching forever on errors. Reported on 1point3acres' Sierra bank; reconstructed in our…Last asked Oct 2026
- +1Fix a bug in an unfamiliar repo with an AI assistantCodingYou get a small full-stack repository, a reported defect and an AI coding assistant in the browser. Reproduce the problem, find the root cause, fix it and show the fix works…Last asked Sep 2026
- Tell me about a time you went beyond your responsibilitiesBehavioralDescribe a time you took on a problem nobody had assigned to you: an inefficient team process you fixed, a tool that helped teams beyond your own, a risky project you owned end to…Last asked Sep 2026
- Tell me about a time you met a tight deadlineBehavioralDescribe a project with a deadline that was hard to meet. Say when you saw the plan was at risk, what you personally did (cut scope, re-plan, ask for help), how you told…Last asked Sep 2026
- +1Work style and situational judgment assessmentBehavioralSome online assessments include a part with no code at all. You read short workplace scenarios and rate or rank possible responses, then choose between pairs of statements about…Last asked Sep 2026
- Route requests to the nearest healthy data centerCodingBuild a router that processes commands: register a data center with its latitude, longitude and capacity, mark data centers up or down, report the great-circle distance between…Last asked Sep 2026
Why this company, why this role, and why nowBehavioralIntroduce yourself, then explain why you want this company and this role, and why you are looking to move now. Name a few traits that make you a fit for the team, account for past…Last asked Sep 2026
+3Basic calculator IICodingEvaluate a string expression of non-negative integers with +, -, , / and spaces, no parentheses, respecting precedence (integer division truncates toward zero). Variants reported:…Last asked Sep 2026- Parse message definitions and compute their sizesCodingParse text definitions of message types made of typed fields, where a field can be another message type. Report each field's type and each message's total size from given…Last asked Sep 2026
- 2048 game with move, merge and game-over detectionCodingImplement the 2048 game loop: board moves with tile merging, spawning new tiles, and detecting when no move remains. Reported on 1point3acres' Glean bank; reconstructed in our own…Last asked Sep 2026
- Prioritizing testing work under deadline pressureBehavioralFor a QA role: when a deadline puts the project under pressure, how do you decide what to test and organize your work? Use a real situation. A good answer makes the prioritization…Last asked Sep 2026
- Top-k prefix suggestions filtered by departmentCodingA service has a fixed list of suggestions, each (ngram, department, score). Implement getTopSuggestions(query, userDept, k), returning the k best-scoring suggestions that match…Last asked Sep 2026
- Design a work-together distance between two employeesML designDesign a distance d(u1, u2) between any two people in a company that measures how closely they work together: smaller means closer. Decide which signals to use (shared documents…Last asked Sep 2026
- Rate-limited Wikipedia crawler built with an AI assistantCodingWorking with an AI coding assistant (required in this round), build a crawler for Wikipedia that respects a rate limit. Its order follows a coverage rule: pages whose title starts…Last asked Sep 2026
- How would you test a system that counts the leaves on a treeCodingA testing question from a QA engineer loop, left vague on purpose: how would you test a system that counts the leaves on a large tree? First pin down what the system is and what…Last asked Sep 2026
- Rebuild a task tree from parent-child records and print itCodingYou get a list of task records, each naming a task and its parent. Rebuild the hierarchy of tasks and subtasks and print it as a text tree with connector characters, in the exact…Last asked Sep 2026
- Byte-pair encoding tokenizerCodingImplement byte-pair encoding: repeatedly merge the most frequent adjacent pair until the vocabulary reaches its target size, then tokenize with the learned merges. Reported on…Last asked Sep 2026
- Read text values of web elements with SeleniumCodingLocate two web elements and read back their text values with a browser automation script. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026