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Frontier AI technical interview question bank.

Practice coding, system design, behavioral, and project questions for frontier AI roles.

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Home
Question bank

Frontier AI technical interview question bank.

Practice coding, system design, behavioral, and project questions for frontier AI roles.

Company

FREE PRACTICE

Public demos, always pinned.

Start with either demo. They remain here when you filter or sort.

Free account: sign in to practice the marked Free questions.

Newest published questions; deterministic, never randomized.

Demo 1Number search with delayed feedback
Demo 2Design real-time device monitoring and control

Question bank filters

Reset filters

Question groups

Filter question bank by interview groupAll 269 Coding 162 System design 48 Behavioral 29 Hiring manager 16 Project deep dive 14

Topics

Filter question bank by topic tagsAll 269 Python 161 Algorithms 40 Data structures 46 Concurrency 27 Distributed systems 7 Storage & state 43 Networking 7 Reliability 30 ML / AI 27 Data / SQL 24 Security 7 Product design 25 Communication 66

Independent and not affiliated with the companies represented. Collected material does not predict future interview questions.

239 questions

Sort question bankSortFree first Newest Oldest AI ratio ↓AI ratio ↑

Question bank results

Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Count distinct values in an ordered list

Given a nondecreasing integer sequence, report how many different values it contains.

Practice focusRequirements - The input is one line of space-separated integers in nondecreasing order. - Equal values are therefore adjacent, and the sequence may contain negative values. - Return the number of distinct values as a decimal string. - You do not need to print or return the compacted sequence itself. - run case(case: dict) forwards case["stdin"] to solve . - Do not append a trailing newline to the returned string; return the value exactly once.

Free practice

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Zero rows and columns around each zero

Given a matrix, set every cell in a row or column that contains a zero to zero, deciding which rows and columns to clear from the original values rather than from the partially rewritten matrix.

Practice focusRequirements - Line 1 is rows cols . The next rows lines each hold cols integers. - For every cell that is 0 in the original matrix, its entire row and entire column become 0 . - Decide all affected rows and columns before writing any zeros, so zeros created by the update must not widen the cleared area. - Return the matrix with rows in their original order, values separated by single spaces and rows separated by newlines, with no extra text. - A matrix with no zeros is returned unchanged. - run case(case: dict) forwards case["stdin"] to solve .…

Free practice

Topic tags
Python
Storage & state

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Normalize an absolute filesystem path

Read one absolute path and return its canonical form: empty segments and . segments disappear, .. folds into the parent, and exactly one slash separates the surviving directories.

Practice focusRequirements - The input is a single absolute path; it may repeat separators and may end with a slash. - A whole segment equal to . is dropped; only a whole segment equal to .. means "go up". - .. removes the most recently kept segment; when nothing is left to remove it has no effect, so climbing past the root stays at the root. - Join the remaining segments with one leading slash, no doubled slashes, and no trailing slash. - Return / alone when no segment survives.…

Free practice

Topic tags
Python
Data structures
Product design

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Dot product of two long integer vectors

Read a shared length and two integer vectors of that length, then return their dot product as a decimal string. Most entries are zero, so the useful work should follow the non-zero positions rather than the dec…

Practice focusRequirements - Line 1 is the length n ; line 2 holds n integers for the first vector; line 3 holds n integers for the second. - Some inputs carry the two characters backslash and n instead of real line breaks; treat both forms as line separators before parsing. - Multiply matching positions, then add the products. Entries may be negative, so the sum can be negative or zero. - Return the total as a plain decimal string with no padding, no plus sign, and no newline. - Do not print the individual products or the operand vectors.…

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Detect any contiguous run with a target sum

Given an integer array and a target, decide whether some non-empty contiguous run adds up to exactly that target.

Practice focusRequirements - The first line holds the element count and the target, separated by a space; the second line holds the values. - Return True when at least one such run exists and False otherwise, with exactly that capitalization and no other text. - Values may be negative or zero, so a partial sum that drifts away from the target is not evidence that no run exists. - A single element equal to the target counts, and a run may include zero-valued elements. - Stop as soon as a match is found; later runs do not change the answer.…

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Water held between bars

Bars of width one stand along a line at the given heights. Return how many units of water stay trapped between them after it rains.

Practice focusRequirements - Line 1 is the bar count; line 2 lists the height of each bar from left to right. - The water above a bar is bounded by the shorter of the tallest bars on its left and on its right, minus the bar's own height. - Bars at the two ends hold nothing, and a stretch that only falls or only rises holds nothing. - Return the total as a decimal string with no per-bar breakdown and no trailing newline. - Heights are non-negative integers; the total fits in ordinary integer arithmetic. - An input with zero or one bar traps nothing.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Resolve a cd target against a working directory

You are given an absolute working directory and the argument of a cd command. Return the absolute directory the shell would land in once ., .., and repeated separators are collapsed.

Practice focusRequirements - Line 1 is an absolute working directory; line 2 is the argument, which may be absolute or relative. - An absolute argument discards the working directory and is resolved from the root. - . keeps the current directory, .. moves to the parent, and climbing past the root stays at / . - Only a whole segment equal to . or .. is special; a name such as file..name remains one segment. - Return the path with one leading slash, no repeated or trailing separators, and / alone when nothing remains.…

Free practice

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Palindrome after at most k deletions

Given a lowercase string and a deletion limit, decide whether removing at most that many characters can leave a palindrome while the surviving characters keep their order.

Practice focusRequirements - Line 1 is the string; line 2 is the integer limit. - Removing nothing is allowed, so a string that already reads the same in both directions always qualifies. - Each deletion is a single character, and characters that are kept never change position relative to each other. - On a mismatched pair, only two moves are worth trying: drop the left character or drop the right one. - Return true or false in lowercase, with no other text and no extra whitespace.…

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Words ordered by a custom alphabet

An ordering is supplied as a permutation of the letters. Decide whether the given word list is sorted according to that ordering.

Practice focusRequirements - Line 1 is the word count; that many words follow one per line; the final line is the ordering, a permutation of the twenty-six lowercase letters. - The final line is always the ordering, so the count line only says how many words precede it. - Compare adjacent words left to right and stop at the first position where the letters differ; the letter ranked earlier wins. - If one word is a proper prefix of the other, the shorter word must appear first. - Return true or false in lowercase, with no other text.…

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Segment text with a word list

Given a text and a small dictionary, decide whether the whole text can be written as a sequence of dictionary words, reusing a word as often as needed.

Practice focusRequirements - Line 1 is the text; line 2 is how many dictionary words follow, one per line. - Some inputs carry the two characters backslash and n instead of real line breaks; treat both forms as line separators before parsing. - Every character of the text must be covered in order by whole dictionary words; nothing may be skipped or reordered. - Words may be reused, and a word may be shorter than the remaining text but must match exactly at the current position. - Return true or false in lowercase, with no other text.…

New public brief

Topic tags
Storage & state
Product design

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodSep 2026

Design real-time device monitoring and control

Design a service that ingests telemetry from many devices, detects meaningful state changes, and triggers control actions according to configurable rules.

Practice focusCover the ingestion API, event schema, message transport, stream processing, state storage, rule evaluation, and command-delivery path. Explain how the system handles bursty traffic, duplicate and out-of-order events, intermittent device connectivity, failed control commands, and service recovery. Define the latency and consistency guarantees you would offer, the metrics needed to operate the system, and the safeguards that prevent unstable feedback loops. Follow-ups 1. Support devices that remain offline for days and later upload buffered telemetry. 2.…

New public brief

Topic tags
Python

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodSep 2026

Number search with delayed feedback

A hidden integer lies in the inclusive range 1..n, where n >= 1. The test fixture supplies a check(x) callback. Your code must not implement the callback and is not given the hidden integer.

Practice focusEach call to check(x) submits a new integer guess in 1..n , but returns the comparison result for the previous submitted guess: - the first call returns None ; - -1 means the previous guess was too high; - 0 means the previous guess was correct; and - 1 means the previous guess was too low. Implement: Return the hidden integer. The fixture validates the answer and permits at most 2 n.bit length() calls to check . Track which guess each delayed response describes; do not apply a response to the newly submitted guess.…

New public brief

Topic tags
Python
Algorithms
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Implement 1-nearest-neighbor classification as a linear layer

You are given a matrix of labeled training examples and a batch of query examples. Implement squared-Euclidean 1-nearest-neighbor classification, then show that the same nearest-neighbor choice can be expressed…

Practice focusScenario You are given a matrix of labeled training examples and a batch of query examples. Implement squared-Euclidean 1-nearest-neighbor classification, then show that the same nearest-neighbor choice can be expressed as the output of an affine layer. For a query vector x and training vector x i : -||x - x i||² = 2x·x i - ||x i||² - ||x||² The final term is constant across all training examples for a fixed query, so it does not affect the winning index. This yields an affine score matrix with W = 2 X train.T and b i = -||x i||² .…

New public brief

Topic tags
Python
Algorithms

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Infection Spread on a Grid

A grid contains healthy cells (0) and infected cells (1). Each day, infection spreads simultaneously from infected cells to their four orthogonal healthy neighbors. Return the number of days until every suscept…

Practice focusRequirements - All initially infected cells spread at the same time. - Return 0 when no healthy cell exists initially. - Do not allow newly infected cells to spread again during the same day. - Handle empty grids and validate rectangular input. - Target O(rows cols) time and space proportional to the active frontier. In the second stage, cells marked 2 are immune: they never change and block propagation. Follow-ups 1. Add recovery after a configurable number of days. 2. Require at least q infected neighbors before a cell changes. 3.…

New public brief

Topic tags
Python
Data structures

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Aggregate Labels from Noisy Annotators

You receive labels from multiple annotators, with missing entries. Infer one binary label per item, identify annotators who systematically disagree with their peers, remove them, and recompute the labels.

Practice focusAssumptions Rows are annotators, columns are items, labels are 0 , 1 , or -1 for missing. Majority ignores missing entries and ties resolve to 1 . An annotator is bad when agreement with provisional labels on overlapping items is strictly below 0.5 . If gold is supplied, also return accuracy rounded to a stated precision. Requirements - Define behavior for items with no labels and annotators with no overlap. - Avoid treating missing values as votes. - Recompute the final majority after filtering. - State complexity and numerical representation.…

Public brief

Topic tags
Algorithms

OpenAICodingAI-generated

Talk-through codingNo local grader

Reported interview periodSep 2026

Deal and rank three-card poker hands

Implement the core of a three-card poker game. Cards are dealt to seated players one card at a time over three passes, then every hand is ranked and the winner or winners are returned.

Practice focusScenario Implement the core of a three-card poker game. Cards are dealt to seated players one card at a time over three passes, then every hand is ranked and the winner or winners are returned. Ranks increase from 2 through A . A deck contains one card for every rank and suit combination, and a card may be dealt at most once. Assumed interface The exact public API is intentionally flexible. One coherent option is: State any alternative interface before implementation.…

Public brief

Topic tags
Python

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Expiring compute-credit ledger

Implement a ledger for compute-credit grants and debits whose events may arrive out of order.

Practice focusEach grant has a unique ID, amount, activation timestamp, and expiration duration. A grant is available through its expiration boundary. subtract(amount, timestamp) consumes credits that expire soonest. get balance(timestamp) returns the balance that would have been available at that point in time by evaluating all applicable events in chronological order. Define deterministic behavior for duplicate IDs, insufficient balance, equal timestamps, and late-arriving events. Preserve enough history to answer past-balance queries correctly. Follow-ups 1.…

Public brief

Topic tags
Communication

OpenAIHiring manager

Discussion / designResponse prompt

Reported interview periodNov 2025–Sep 2026

Motivation and impact conversation

Prepare a concise answer to each question:

Practice focus1. Why are you interested in this company and role now? 2. Which parts of the organization’s mission and work connect to your experience? 3. What positive and negative effects could advanced AI have on society? 4. How do safety and alignment considerations influence the way you build products or conduct research? 5. Describe one project that best demonstrates your judgment, ownership, and ability to learn. Use specific evidence from your own work. State your reasoning and trade-offs rather than relying on generic mission language.…

Public brief

Topic tags
Storage & state
Product design

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodFeb 2026–Sep 2026

Design a browser IDE for many users

Design a browser-based development environment where users can open persistent workspaces, edit files, run programs, and interact with a live terminal.

Practice focusCover workspace storage, process isolation, scheduling, standard-output streaming, terminal input, reconnect after refresh, dependency setup, and file synchronization. Explain how you prevent one user’s code from affecting another user or the host system. Address cold-start latency, idle-workspace suspension, resource quotas, long-running jobs, failure recovery, observability, and the trade-off between warm capacity and infrastructure cost. Follow-ups 1. Support collaborative editing without coupling file consistency to terminal I/O. 2.…

Public brief

Topic tags
Communication

OpenAIProject deep diveAI-generated

Discussion / designResponse prompt

Reported interview periodDec 2025–Sep 2026

Technical project deep dive

Lead a structured discussion of one technically substantial system you personally helped build. Choose a project with real constraints, meaningful decisions, and at least one outcome you can quantify. The goal …

Practice focusScenario Lead a structured discussion of one technically substantial system you personally helped build. Choose a project with real constraints, meaningful decisions, and at least one outcome you can quantify. The goal is to demonstrate engineering judgment and ownership, not to present a polished product pitch. Suggested structure 1. Context: Who used the system, what problem mattered, and what was explicitly out of scope? 2. Constraints: Scale, latency, reliability, privacy, staffing, deadlines, legacy dependencies, or cost. 3.…

Public brief

Topic tags
Python
Data structures
Concurrency
Networking

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodFeb 2026–Sep 2026

IPv4 and CIDR Iterator

Implement an iterator that walks IPv4 addresses from a seed, either forward, backward, or within the seed's CIDR block.

Practice focusRequirements - Accept a plain IPv4 address or CIDR such as 10.2.3.4/24 . - Include the seed as the first result. - Forward iteration ends at 255.255.255.255 or the block broadcast address. - Backward iteration ends at 0.0.0.0 or the block network address. - Validate octets, prefix lengths, and direction; raise StopIteration after exhaustion. - Use integer address arithmetic rather than incrementing dotted components as strings. State whether network and broadcast addresses are included; for this problem, include both boundaries. Follow-ups 1.…

Public brief

Topic tags
Concurrency
Storage & state
Security

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodFeb 2026–Sep 2026

Design an Online Chess Service

Design a service that matches two players, maintains authoritative legal game state, supports clocks, and allows games to be reviewed later.

Practice focusRequirements - Define APIs or real-time events for matchmaking, moves, resignations, draw offers, reconnects, and spectators. - The server—not the client—validates turns, legal moves, check, checkmate, stalemate, and special rules. - Make duplicate or reordered client messages idempotent. - Maintain fair clocks despite network delay and disconnects. - Persist an append-only move history and enough state for fast reconnect and review. - State scale assumptions, latency goals, and consistency boundaries.…

New public brief

Topic tags
Python

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Sep 2026

Generalized Tic-Tac-Toe

Implement a two-player game on a rows x cols board. A player wins by placing k consecutive marks horizontally, vertically, or along either diagonal.

Practice focusRequirements - Player 1 moves first and players alternate. - move places the current player's mark and returns that player number if the move completes a run of length k ; otherwise return 0 . - After a win, later calls return the existing winner without changing it. - Initially assume coordinates are valid and empty; explain how production code would reject invalid moves. - Support rectangular boards and k smaller than either dimension. - Avoid scanning the entire board after every move.…

New public brief

Topic tags
Python

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Revenue Tracking with Direct Referrals

Build a customer revenue index. Each inserted customer has personal revenue and may name an existing customer as a referrer. A customer's total revenue is personal revenue plus the personal revenue of direct re…

Practice focusRequirements - Assign IDs starting at 0 in insertion order. - If a referrer is provided, update that customer's total by the new customer's personal revenue. - A customer's referrals do not contribute to its referrer's total; attribution is one level only. - The query considers totals at least min total revenue , orders by (total revenue, id) , and returns at most k IDs. - Validate non-negative revenue, valid referrers, and non-negative k .…

Previous5 of 10Next

Browse all original practice

Build a token-budget batcher
Sliding-window rate limiter
Interval calendar
Nested dictionary transforms
Command-log store
Dependency-ready scheduler
Streaming metric window
Evaluation slice aggregator
Build a reliable job runner
Build one adaptable decision story
Defend your role fit
Prepare one project deep dive
Design an evaluation artifact registry
Defend a reversible launch decision
Negotiate an ambiguous role scope
Trace a project from claim to evidence
Choose between two urgent priorities
Resolve a cross-functional disagreement
Own a consequential failure
Increase a team’s leverage
Warm a cold cache without a thundering herd
Ship a 500 GB checkpoint without a startup stampede
Make every document decision traceable to evidence
Share eight GPUs between two workloads with different promises
A mutable indexed sequence that must restart exactly
Trace a falling unit price to a rising bill
Keep a very long conversation usable while it streams
Design durable scheduled publishing
Make speculative code edits safe to accept
Recover a grouping rule from two-word phrases

CONTENT BOUNDARY

Independent frontier AI interview practice. Includes adaptations of collected interview material and original exercises; not official company questions and not affiliated with the companies represented. Collected material does not predict future interview questions. Report a correction.

Loading the question catalog…

FREE PRACTICE

Public demos, always pinned.

Start with either demo. They remain here when you filter or sort.

Free account: sign in to practice the marked Free questions.

Newest published questions; deterministic, never randomized.

Demo 1Number search with delayed feedback
Demo 2Design real-time device monitoring and control

Question bank filters

Reset filters

Question groups

Filter question bank by interview groupAll 269 Coding 162 System design 48 Behavioral 29 Hiring manager 16 Project deep dive 14

Topics

Independent and not affiliated with the companies represented. Collected material does not predict future interview questions.

239 questions

Sort question bankSortFree first Newest Oldest AI ratio ↓AI ratio ↑

Question bank results

Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Count distinct values in an ordered list

Given a nondecreasing integer sequence, report how many different values it contains.

Free practice

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Zero rows and columns around each zero

Given a matrix, set every cell in a row or column that contains a zero to zero, deciding which rows and columns to clear from the original values rather than from the partially rewritten matrix.

Free practice

Topic tags
Python
Storage & state

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Normalize an absolute filesystem path

Read one absolute path and return its canonical form: empty segments and . segments disappear, .. folds into the parent, and exactly one slash separates the surviving directories.

Free practice

Topic tags
Python
Data structures
Product design

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Dot product of two long integer vectors

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Detect any contiguous run with a target sum

Given an integer array and a target, decide whether some non-empty contiguous run adds up to exactly that target.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Water held between bars

Bars of width one stand along a line at the given heights. Return how many units of water stay trapped between them after it rains.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Resolve a cd target against a working directory

You are given an absolute working directory and the argument of a cd command. Return the absolute directory the shell would land in once ., .., and repeated separators are collapsed.

Free practice

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Palindrome after at most k deletions

Given a lowercase string and a deletion limit, decide whether removing at most that many characters can leave a palindrome while the surviving characters keep their order.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Words ordered by a custom alphabet

An ordering is supplied as a permutation of the letters. Decide whether the given word list is sorted according to that ordering.

Free practice

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Segment text with a word list

Given a text and a small dictionary, decide whether the whole text can be written as a sequence of dictionary words, reusing a word as often as needed.

New public brief

Topic tags
Storage & state
Product design

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodSep 2026

Design real-time device monitoring and control

Design a service that ingests telemetry from many devices, detects meaningful state changes, and triggers control actions according to configurable rules.

New public brief

Topic tags
Python

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodSep 2026

Number search with delayed feedback

A hidden integer lies in the inclusive range 1..n, where n >= 1. The test fixture supplies a check(x) callback. Your code must not implement the callback and is not given the hidden integer.

New public brief

Topic tags
Python
Algorithms
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Implement 1-nearest-neighbor classification as a linear layer

New public brief

Topic tags
Python
Algorithms

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Infection Spread on a Grid

New public brief

Topic tags
Python
Data structures

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Aggregate Labels from Noisy Annotators

Public brief

Topic tags
Algorithms

OpenAICodingAI-generated

Talk-through codingNo local grader

Reported interview periodSep 2026

Deal and rank three-card poker hands

Implement the core of a three-card poker game. Cards are dealt to seated players one card at a time over three passes, then every hand is ranked and the winner or winners are returned.

Public brief

Topic tags
Python

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Expiring compute-credit ledger

Implement a ledger for compute-credit grants and debits whose events may arrive out of order.

Public brief

Topic tags
Communication

OpenAIHiring manager

Discussion / designResponse prompt

Reported interview periodNov 2025–Sep 2026

Motivation and impact conversation

Prepare a concise answer to each question:

Public brief

Topic tags
Storage & state
Product design

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodFeb 2026–Sep 2026

Design a browser IDE for many users

Design a browser-based development environment where users can open persistent workspaces, edit files, run programs, and interact with a live terminal.

Public brief

Topic tags
Communication

OpenAIProject deep diveAI-generated

Discussion / designResponse prompt

Reported interview periodDec 2025–Sep 2026

Technical project deep dive

Public brief

Topic tags
Python
Data structures
Concurrency
Networking

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodFeb 2026–Sep 2026

IPv4 and CIDR Iterator

Implement an iterator that walks IPv4 addresses from a seed, either forward, backward, or within the seed's CIDR block.

Public brief

Topic tags
Concurrency
Storage & state
Security

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodFeb 2026–Sep 2026

Design an Online Chess Service

Design a service that matches two players, maintains authoritative legal game state, supports clocks, and allows games to be reviewed later.

New public brief

Topic tags
Python

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Sep 2026

Generalized Tic-Tac-Toe

Implement a two-player game on a rows x cols board. A player wins by placing k consecutive marks horizontally, vertically, or along either diagonal.

New public brief

Topic tags
Python

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Revenue Tracking with Direct Referrals

Previous5 of 10Next

Browse all original practice

Build a token-budget batcher
Sliding-window rate limiter
Interval calendar
Nested dictionary transforms
Command-log store
Dependency-ready scheduler
Streaming metric window
Evaluation slice aggregator
Build a reliable job runner
Build one adaptable decision story
Defend your role fit
Prepare one project deep dive
Design an evaluation artifact registry
Defend a reversible launch decision
Negotiate an ambiguous role scope
Trace a project from claim to evidence
Choose between two urgent priorities
Resolve a cross-functional disagreement
Own a consequential failure
Increase a team’s leverage
Warm a cold cache without a thundering herd
Ship a 500 GB checkpoint without a startup stampede
Make every document decision traceable to evidence
Share eight GPUs between two workloads with different promises
A mutable indexed sequence that must restart exactly
Trace a falling unit price to a rising bill
Keep a very long conversation usable while it streams
Design durable scheduled publishing
Make speculative code edits safe to accept
Recover a grouping rule from two-word phrases

CONTENT BOUNDARY