+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 p
Last asked Oct 2026
Questions
- +1
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
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
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
- 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- 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
- 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
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
- 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
+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
- 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
- +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- +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
- 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
- +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
- +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
- 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
- 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
- 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
- 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
- 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
+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
- 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
- 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
- Sort an array with one misplaced elementCodingSort a nearly sorted array in which a single element sits out of place, faster than a full sort. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
- +3Word search with a word search II follow-upCodingFind words on a letter grid by adjacent moves, then extend the solution to finding many words at once efficiently. Reported on 1point3acres' Glean bank; reconstructed in our own…Last asked Sep 2026
- +1Kth largest element in two sorted arraysCodingFind the kth largest element across two sorted arrays without merging them. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
- Document indexing queue assignmentCodingAssign incoming documents to indexing workers across queues so the load stays balanced as documents arrive. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
- Shortest path through a digit grid with diagonal movesCodingYou are given an m x n grid of digits. A cell holding 0 is a wall; a cell holding 1 through 9 is open. Starting at the top-left cell (0, 0), find a shortest route to the…Last asked Sep 2026
+1Connect Four game engine with win detectionCodingImplement a two-player game of Connect Four. The board has rows rows and cols columns (default 6 x 7). Players "A" and "B" alternate turns, and "A" moves first. On a turn, a…Last asked Sep 2026
+2Greedy and beam search decoding for a language modelCodingYou are writing the decoding step for a language model. Decoding turns the model's per-step scores into a sequence of token ids. Implement greedydecode(scores: listlistfloat) -…Last asked Sep 2026- React social feed with voting, re-sorting and pinned postsCodingBuild a feed page in React. Each post can be upvoted or downvoted, and after every vote the feed re-sorts by score, highest first. A post can be pinned, and pinned posts stay at…Last asked Sep 2026
- Minimum deletions to balance a parentheses stringCodingA string contains only ( and ). Delete as few characters as possible so the rest is balanced, and return the resulting string.Last asked Sep 2026
- Cell with the least total walking distance to all targets around wallsCodingA grid has targets, empty cells and walls. Walking moves up, down, left or right and cannot cross walls. Find a non-wall cell whose summed walking distance to every target is as…Last asked Sep 2026
- Divide a bar into k+1 pieces to maximize the smallest pieceCodingAn array of positive integers describes consecutive chunks of a bar. Make exactly k cuts so the bar becomes k + 1 contiguous pieces, and you keep the piece with the smallest sum…Last asked Sep 2026
- Rank transform of a matrix with distinct valuesCodingGiven an m x n matrix of distinct integers, replace each value with a rank starting at 1 so that in any row or column a larger value gets a larger rank, and ranks are as small as…Last asked Sep 2026
Sizes of connected regions in a binary image, in scan orderCodingA binary image is an m x n grid of 0s and 1s. Foreground pixels (1s) that touch up, down, left or right belong to the same region; diagonal neighbours do not. Return the size of…Last asked Sep 2026- Evaluate divisionCodingYou get equations a / b = value between string variables, each standing for a positive real number, and a large batch of queries c / d. Answer every query from the equations, or…Last asked Sep 2026
- Minimum Manhattan distance between X and Y in a matrixCodingFind the smallest Manhattan distance between any X cell and any Y cell in a matrix. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
- Transitive synonym groups from word contextsCodingGroup words into synonym sets where sharing a four-word context links them transitively. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
- Draw routes on map images fetched from an HTTP APICodingRead a JSON file of places and routes, call a remote map service to download the matching map images, then mark the places and draw lines between them on the images. The task…Last asked Sep 2026
- +4Maximum overlap of closed intervalsCodingGiven a list of closed intervals start, end (both endpoints included), return the largest number of intervals that contain one point on the number line. Two intervals that only…Last asked Sep 2026
- +1GPU credit ledger with out-of-order eventsCodingBuild an in-memory ledger for GPU credits. Credit arrives as grants: each one has a unique id, an amount, and a time window in which it can be spent. Grants may overlap in time…Last asked Sep 2026
- +3Threshold infection spread on a gridCodingA lab tracks a disease across a rectangular field of cells. You are given an m x n grid where 0 is a healthy cell and 1 is an infected cell, and an integer threshold. Each day…Last asked Sep 2026
- Match payments to invoices by memo and amountCodingA billing system has to match incoming payments to open invoices. Both arrive as comma-separated strings. - Invoice: invoiceid,amount,duedate. The amount is an integer in cents…Last asked Sep 2026
- +4Group dependent tasks into parallel levelsCodingYou run a build system. Each task has a unique, non-empty lowercase name. Some tasks depend on others: a dependency before, after means before must finish before after can start…Last asked Sep 2026
- Monthly AI token billing with plan switchingCodingYou are building the monthly invoice step for a chat-based AI product that charges by token usage. Each chat session produces one record, given as a comma-separated string with…Last asked Sep 2026
Squares of a sorted array, then the k smallest squaresCodingYou get an integer array sorted in non-decreasing order; it may hold negative numbers. 1. Return the squares of all its elements in sorted order, faster than sorting again (O(n)…Last asked Sep 2026- +4Number of islandsCodingGiven a binary matrix, return how many islands it has: groups of 1 cells connected up, down, left or right (diagonals don't connect).Last asked Sep 2026
- +1Hardware design verification fundamentalsCodingDiscuss and sketch verification for common hardware blocks: a FIFO, a round-robin arbiter and a valid/ready handshake. Cover scoreboards and reference models, constrained random…Last asked Sep 2026
- +2Encode and decode strings with length prefixes and count codesCodingSerialize a list of arbitrary strings into one string and back without ambiguity. A second variant decodes a compact code where some letters are written as two digits with a…Last asked Sep 2026
- Effective privileges in a role hierarchy with allow and disallow listsCodingYou are building the access-control layer of a data platform. Every role has: - allowed: privileges granted directly to the role - disallowed: privileges explicitly taken away…Last asked Sep 2026
- Three-card showdown between two playersCodingDesign a two-player card game that uses a standard 52-card deck. Each card has a rank and a suit. From lowest to highest, the ranks are 2 3 4 5 6 7 8 9 10 J Q K A. The suits are C…Last asked Sep 2026
- Insert, delete and get random in O(1) with duplicatesCodingDesign a collection of integers that allows duplicates and supports, each in average O(1) time: 1. insert(val): add one copy of val; return whether val was absent before. 2…Last asked Sep 2026
- Build reporting trees from employee-manager pairsCodingYou get a list of employee, manager pairs, where each person is a positive integer id and the pair means the employee reports directly to that manager. Build the org chart…Last asked Sep 2026
- Reversi move simulation with captures in 8 directionsCodingImplement one move of the board game Reversi (also sold as Othello). You get an n x n board as a list of lists of characters. Each cell is 'B' (black), 'W' (white) or '.' (empty)…Last asked Sep 2026
- Unit conversion ratio queries with modular answersCodingYou have n units, numbered 0 to n - 1, split into separate families: units in one family convert into each other, units from different families never do. You are given conversion…Last asked Sep 2026
- +1Vectorized nearest-neighbour classifier as a linear layerCodingImplement a 1-nearest-neighbour classifier in NumPy with no Python loops. Then rewrite it as the forward pass of a small network, a matrix product plus a bias followed by an…Last asked Sep 2026
- +1Find noisy annotators and retrain a classifier without themCodingA classifier is trained on labels from several human annotators, and some of them label carelessly. Find which annotators are unreliable, drop their labels, retrain, and show…Last asked Sep 2026
- Deployment windows in a recurring weekCodingDeployments are planned on a recurring week measured in minutes, from 0 to 10,079, and the same schedule repeats every week. Teams declare windows in which deployment is allowed…Last asked Sep 2026
- +2Implement k-means clusteringCodingImplement k-means from scratch: initialize k centroids, assign every point to its nearest centroid, move each centroid to the mean of its points, and repeat until the assignments…Last asked Sep 2026
- +1Task manager with user quotas and expiring assignmentsCodingBuild an in-memory TaskManager in four levels. Each level adds methods to the same class, and you move to the next level only after the current one passes. Every method takes an…Last asked Sep 2026
- Explore a friend graph through a remote API with few callsCodingYou cannot read a social graph directly; the only access is getfriends(userid), a remote call that returns a user's friends and costs a network round trip. Write code that…Last asked Sep 2026