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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.

217 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.

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 .…

Public brief

Topic tags
Python
Data structures
Concurrency
Storage & state
Reliability

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodAug 2026–Sep 2026

Leased Work Queue with Dead-Letter Handling

Implement an in-memory queue whose jobs are reserved with expiring leases. A failed worker must not hold a job forever, and jobs that exceed their retry budget move to a dead-letter state.

Practice focusRequirements and assumptions - Jobs move among ready , reserved , completed , and dead . - reserve increments attempts and returns {item id, token} plus an internal deadline. - On explicit failure or lease deadline <= now , return the job to ready unless attempts reached max attempts ; then mark it dead. - Completion or failure with a stale token returns False without changing state. - Queue ready jobs deterministically and reject duplicate active IDs. - Validate positive limits and use the explicit clock supplied by callers. Follow-ups 1.…

New public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Sep 2026

Evaluate an arithmetic string

Write solve(raw: str) -> str that evaluates one arithmetic expression and returns its integer value as text.

Practice focusRequirements - The expression contains non-negative integers, single spaces, and the operators + , - , , and / . There are no parentheses, no unary minus, and no exponentiation. - and / bind more tightly than + and - ; work left to right inside each precedence level. - / is integer division that truncates toward zero, so -3/2 truncates to -1 if a lead-in subtraction makes the intermediate negative. - Ignore every space and read the run of digits between operators as one number.…

Public brief

Topic tags
Product design

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodJan 2026–Sep 2026

Design hold-then-charge payments

Design a payment platform with two operations:

Practice focus- hold synchronously requests authorization from a downstream card network and must return approval or rejection within a 500 ms p95 target. - charge references an approved hold, durably records the request, acknowledges it, and includes it in a later settlement batch. Assume 10 million holds and 8 million charges per day, peaks near 300 requests per second, 5–10 downstream networks, a two-hour nightly settlement window, and a seven-day hold lifetime.…

Public brief

Topic tags
Python
ML / AI

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Debug a minimal transformer computation

A small NumPy model produces incorrect attention outputs and fails to learn. Implement corrected versions of four operations used by a decoder-style model. The model dimension is small and attention uses one he…

Practice focusScenario A small NumPy model produces incorrect attention outputs and fails to learn. Implement corrected versions of four operations used by a decoder-style model. The model dimension is small and attention uses one head, so focus on tensor semantics rather than framework APIs. Interface Requirements pos embed Return token representations with positional embeddings added elementwise. Shapes must match or broadcast unambiguously. attention - Compute scaled dot-product attention using a scale of 1 / sqrt(d k) .…

New public brief

Topic tags
Python
Data structures
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Minimize Encryption Work in a File Tree

A file hierarchy contains directories and files. Some files are already encrypted. You may encrypt an individual file or issue one recursive encryption request for an entire directory. Choose operations with mi…

Practice focusRequirements and cost model - Encrypting one file costs t req + t file . - Encrypting a directory costs t req + N t file , where N is every file in its subtree, including already-encrypted files. - A subtree with no unencrypted files costs 0 . - At a directory, you may batch the whole subtree or solve its children independently. count files returns (encrypted count, unencrypted count) . The input is a finite tree of FileNode and DirectoryNode objects, with boolean encryption flags, no cycles or shared nodes, and non-negative integer costs.…

Public brief

Topic tags
Python
Data structures
Distributed systems

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Sep 2026

Aggregate Count and Topology over a Machine Tree

Machines form a rooted tree and may communicate only with their parent or children. Implement message handling so the root can count all machines and reconstruct a deterministic topology string.

Practice focusRequirements - A count request propagates to children; a leaf replies 1 ; an internal node replies with one plus all child counts. - A topology request produces id(child1,child2,...) ; a leaf is id[] . - Only the root publishes the final result. - Correlate replies with operation type and wait for every expected child exactly once. - Do not assume child replies arrive in order; sort by child ID for deterministic topology. - Avoid blocking the message handler and state behavior for duplicate requests.…

New public brief

Topic tags
Python
Algorithms

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Contagion in a Grid

A rectangular grid contains empty cells (0), fresh items (1), and contaminated items (2). At each minute, every fresh item sharing an edge with a contaminated item becomes contaminated. All changes within a min…

Practice focusImplement: Return the number of minutes required for every fresh item to become contaminated. Return 0 if there are no fresh items initially, and -1 if at least one fresh item is unreachable. Diagonal neighbors do not interact. Aim for O(rows columns) time and space. Staged follow-ups 1. Return the earliest arrival time for every reachable cell from multiple sources. 2. Introduce blocked cells and targets, returning the time when all targets are reached. 3. You may remove at most one shared blocker for the entire propagation.…

New public brief

Topic tags
Python
Algorithms
Concurrency

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Shortest maze route with collected keys

Guide a walker from the start cell to the exit of a character grid, where locked doors stay shut until the matching key has been picked up, and report the fewest single-cell moves needed.

Practice focusRequirements - Line 1 gives rows cols . The next rows lines each contain exactly cols characters. - . is open floor, blocks movement, S is the start, and E is the exit. - Lowercase letters a through f are keys. Uppercase A through F are doors that require the key with the same letter. - E marks the exit and is never read as the door for key e . - A collected key is kept permanently, so the walker may revisit a cell with a different set of keys. - Each move changes the row or column by one. Entering a door without its key is not allowed.…

New public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Stamp a supplied route onto a grid

Mark the open floor cells named in a coordinate list and return the resulting grid, leaving walls, the start, and the exit exactly as they were.

Practice focusRequirements - Line 1 is rows cols . The next rows lines are the grid, each exactly cols characters long. - A count follows the grid, then that many lines of row col . - Coordinates are zero-based and name the row first, then the column. - Replace a . at a listed coordinate with . If the cell holds S , E , , or is already , leave it unchanged. - Listing the same coordinate again has no additional effect. - Return the whole grid with each row on its own line, rows separated by a newline, and no extra text. - Every coordinate is inside the grid.…

New public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Shortest route through directional cells

Compute the fewest orthogonal moves from the start to the exit of a grid containing cells that can only be entered while travelling in one particular direction.

Practice focusRequirements - Line 1 gives rows cols . The next rows lines each contain exactly cols characters. - is a wall, S is the start, and E is the exit. - can be entered only by moving right into it. < can be entered only by moving left into it. - The restriction applies when entering a directional cell. Once inside, the walker may leave in any direction. - S , E , and ordinary open cells accept entry from any side. - Each move goes one cell up, down, left, or right and costs one step.…

New public brief

Topic tags
Python

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Compute File-System Size

A file-system node is either a file with a non-negative byte size or a directory containing child nodes. Hard links are possible, so the same node object may be reachable by more than one path and cycles may ex…

Practice focusImplement: Return the sum of the sizes of all distinct reachable files. Count a node at most once even if multiple paths reference it. An empty directory has size 0 . You may identify nodes by stable object identity. Aim for O(V + E) time and O(V) auxiliary space, where V is the number of distinct reachable nodes and E is the number of child references. Staged follow-ups 1. Provide an iterative traversal for inputs too deep for recursion. 2. Add memoization for repeated directory-size queries. 3.…

New public brief

Topic tags
Python
Algorithms
Concurrency

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Choose the Best Transit Mode Through a Grid

A grid contains a start S, a destination D, blocked cells, and cells labeled by transit mode. A trip must use one mode for its entire route. Choose the reachable mode with the best travel time and cost.

Practice focusRequirements - Digit '1' identifies modes[0] , digit '2' identifies modes[1] , and so on. - Movement is allowed in four cardinal directions through cells of the chosen digit. - S and D may be entered for free and add neither time nor cost. - X , unrelated mode digits, and any other symbols are blocked. - For a route using mode i , each mode cell contributes times[i] and costs[i] . - Choose minimum total time, then minimum total cost, then earlier position in modes . Return "" if no mode reaches D .…

New public brief

Topic tags
Python
Algorithms

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Islands in a Dynamic Grid

You are given a rectangular binary grid. 1 represents land and 0 represents water. Cells belong to the same island when they share an edge; diagonal contact does not connect islands.

Practice focusFirst implement: Then support a grid that begins as all water. After each (row, column) operation, turn that cell into land and report the current island count: Adding an already-land cell leaves the count unchanged. Assume coordinates are in bounds. Staged follow-ups 1. Compare DFS, BFS, and disjoint-set solutions for the static problem. 2. Achieve near-constant amortized work per addition with union by rank and path compression. 3. Discuss the harder case in which land can also be removed.

New public brief

Topic tags
Python
Distributed systems
Storage & state
Reliability

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Circuit Breaker and Replica Failover

Implement a circuit breaker that protects a dependency after repeated failures, then use it to route work across database replicas.

Practice focusRequirements - CLOSED permits calls. A success resets the consecutive-failure count. - After failure threshold consecutive supplier failures, transition to OPEN and propagate the failure. - While OPEN , reject calls without invoking the supplier. - Raise the provided CircuitOpenError for breaker-generated denial; propagate supplier errors unchanged. An error message containing the word OPEN is not a denial signal. - After recovery timeout , permit one HALF OPEN probe. Success closes the breaker; failure reopens it and restarts the timeout.…

Public brief

Topic tags
Python
Algorithms
Concurrency
Product design

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodFeb 2026–Aug 2026

Parallel Prefix Matrix Products with Autograd

Given square matrices W[0..n-1], compute inclusive prefix products P[i] = W[0] @ ... @ W[i] using a Hillis–Steele doubling scan, then implement the backward pass without relying on an automatic-differentiation …

Practice focusRequirements - weights has shape (n, d, d) ; return prefixes with the same shape. - Each scan round combines entries 2 r positions apart, using out-of-place round updates so values from one round are not mixed with the next. - Backward returns the gradient for every input matrix for an arbitrary gradient on every prefix. - Handle n=0 , n=1 , non-commutativity, and floating-point dtype consistently. - Explain saved intermediates and complexity in sequential work, parallel depth, and memory. Follow-ups 1.…

Public brief

Topic tags
Python
Data structures
Concurrency

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Aug 2026

Mode-Compatible Lock with Fair Batching

Implement a lock that may be held concurrently by many threads only when they request the same mode. A different mode waits until all current holders release. Then add fairness across queued modes.

Practice focusRequirements - try acquire grants immediately or queues (tid, mode) without duplicates. - release releases one holder of that mode and returns newly granted thread IDs. - Base lock may admit a new same-mode requester while that mode is active. - Fair lock prevents barging once another mode is queued. - When the next queued mode becomes eligible, grant the contiguous batch already waiting for that mode. - Reject invalid releases and define per-thread ownership. Follow-ups 1. Implement blocking acquire with a condition variable. 2.…

New public brief

Topic tags
Python
Algorithms
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Sum the in-range values of a search tree

Add up every node value that falls inside a closed interval in a binary search tree supplied as a level-order sequence.

Practice focusRequirements - Line 1 lists the tree in level order, comma separated, with null marking a missing child. - Line 2 holds low,high , both endpoints included. - Return the sum of all node values v with low <= v <= high as a decimal string. - Return "0" when the first token is null or when no value lies in the range. - The listing describes a valid binary search tree. - run case(case: dict) forwards case["stdin"] to solve . - Do not append a trailing newline to the returned string; return the value exactly once.

Public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Palindrome after one deletion

Decide whether a lowercase string becomes a palindrome when at most one character is removed.

Practice focusRequirements - The input is a single line holding the string; a trailing newline is formatting, not part of the value. - Removing nothing is allowed, so a string that already reads the same in both directions returns true . - On the first mismatched pair, exactly one of the two candidate removals can help; check both remainders. - Return true or false in lowercase, with no other text. - A one-character string qualifies, and so does an empty one. - Removing more than one character is a different task and is out of scope.

New public brief

Topic tags
Python

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Optimize a Numerical Kernel Under a Fixed Benchmark

You are given a correct but slow numerical kernel, representative inputs, a correctness checker, and a benchmark. Improve its measured throughput without changing its output contract.

Practice focusAssumption: the precise production kernel and hardware contract are unavailable in this preparation version. Begin by implementing and optimizing compatible rectangular matrix multiplication over numeric arrays: Reject incompatible or ragged inputs. Preserve numerical correctness within the stated tolerance and do not special-case benchmark inputs. For this preparation interface, matrices are nonempty rectangular lists with nonempty rows and finite real entries (booleans are not numbers).…

Public brief

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodApr 2026–Aug 2026

Design Photo Sharing with Content Deduplication

Design a photo-sharing service where users upload images, view their libraries, and share content. Identical bytes should be stored once, while near-duplicate detection may assist organization or moderation.

Practice focusRequirements - Define upload, finalize, view, share, and delete APIs. - Hash content during upload and map user-owned logical objects to immutable blobs. - Preserve authorization: discovering that another user uploaded the same bytes must not leak their identity or metadata. - Make concurrent identical uploads safe and avoid duplicate blob writes. - Delete a blob only after no authorized logical object references it, including delayed or failed workflows.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Ancestor lookup with upward-only links

Every node in a tree stores only the id of its parent. Given two node ids, find their deepest shared ancestor using those upward links alone.

Practice focusRequirements - Line one is the node count n . Line two gives n parent ids in node order: the value at position i is the parent of node i , and a root is marked -1 . - Line three holds the two query ids separated by whitespace. - Node identity is the array position, so ids run from 0 to n - 1 . - A node counts as an ancestor of itself, so querying a node against one of its descendants returns that node. - Return the id of the deepest common ancestor as a decimal string, or -1 when the two nodes belong to different trees.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Shared ancestor of two nodes in a binary tree

A binary tree arrives in level-order form along with two node values. Identify the lowest node whose subtree contains both values.

Practice focusRequirements - Line one is the level-order values separated by commas; null marks a missing child and the line may be wrapped in [...] . - Line two holds the two target values separated by a comma. - Node values are unique, and both targets appear in the tree. - A node counts as its own descendant, so a parent and child query answers the parent. - Return the value of the lowest shared ancestor as a decimal string, not its position in the serialization. - When one candidate ancestor lies below another, report the deeper one.…

New public brief

Topic tags
Python
Data structures

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodAug 2026

Independent Lazy Iterators

Implement a utility that turns one input iterable into n iterators. Every returned iterator must yield the full source sequence in order, and consumers may advance at different speeds. Read each source value on…

Practice focusRaise ValueError when n < 1 . Source exceptions and exhaustion should propagate consistently to every consumer. Concurrent calls are out of scope for the initial implementation. Start with a correct design, then improve its memory usage so that buffered values are shared rather than copied into n independent queues. Space should be proportional to the distance between the fastest and slowest consumers plus per-consumer cursor state. Staged follow-ups 1. Explain when buffered values can safely be discarded. 2.…

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.

217 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.

New public brief

Topic tags
Python

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Revenue Tracking with Direct Referrals

Public brief

Topic tags
Python
Data structures
Concurrency
Storage & state
Reliability

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodAug 2026–Sep 2026

Leased Work Queue with Dead-Letter Handling

Implement an in-memory queue whose jobs are reserved with expiring leases. A failed worker must not hold a job forever, and jobs that exceed their retry budget move to a dead-letter state.

New public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Sep 2026

Evaluate an arithmetic string

Write solve(raw: str) -> str that evaluates one arithmetic expression and returns its integer value as text.

Public brief

Topic tags
Product design

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodJan 2026–Sep 2026

Design hold-then-charge payments

Design a payment platform with two operations:

Public brief

Topic tags
Python
ML / AI

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Sep 2026

Debug a minimal transformer computation

New public brief

Topic tags
Python
Data structures
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Minimize Encryption Work in a File Tree

Public brief

Topic tags
Python
Data structures
Distributed systems

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Sep 2026

Aggregate Count and Topology over a Machine Tree

Machines form a rooted tree and may communicate only with their parent or children. Implement message handling so the root can count all machines and reconstruct a deterministic topology string.

New public brief

Topic tags
Python
Algorithms

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Contagion in a Grid

New public brief

Topic tags
Python
Algorithms
Concurrency

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Shortest maze route with collected keys

Guide a walker from the start cell to the exit of a character grid, where locked doors stay shut until the matching key has been picked up, and report the fewest single-cell moves needed.

New public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Stamp a supplied route onto a grid

Mark the open floor cells named in a coordinate list and return the resulting grid, leaving walls, the start, and the exit exactly as they were.

New public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Sep 2026

Shortest route through directional cells

Compute the fewest orthogonal moves from the start to the exit of a grid containing cells that can only be entered while travelling in one particular direction.

New public brief

Topic tags
Python

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Sep 2026

Compute File-System Size

New public brief

Topic tags
Python
Algorithms
Concurrency

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Choose the Best Transit Mode Through a Grid

New public brief

Topic tags
Python
Algorithms

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Islands in a Dynamic Grid

You are given a rectangular binary grid. 1 represents land and 0 represents water. Cells belong to the same island when they share an edge; diagonal contact does not connect islands.

New public brief

Topic tags
Python
Distributed systems
Storage & state
Reliability

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Circuit Breaker and Replica Failover

Implement a circuit breaker that protects a dependency after repeated failures, then use it to route work across database replicas.

Public brief

Topic tags
Python
Algorithms
Concurrency
Product design

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodFeb 2026–Aug 2026

Parallel Prefix Matrix Products with Autograd

Public brief

Topic tags
Python
Data structures
Concurrency

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Aug 2026

Mode-Compatible Lock with Fair Batching

Implement a lock that may be held concurrently by many threads only when they request the same mode. A different mode waits until all current holders release. Then add fairness across queued modes.

New public brief

Topic tags
Python
Algorithms
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Sum the in-range values of a search tree

Add up every node value that falls inside a closed interval in a binary search tree supplied as a level-order sequence.

Public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Palindrome after one deletion

Decide whether a lowercase string becomes a palindrome when at most one character is removed.

New public brief

Topic tags
Python

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Optimize a Numerical Kernel Under a Fixed Benchmark

You are given a correct but slow numerical kernel, representative inputs, a correctness checker, and a benchmark. Improve its measured throughput without changing its output contract.

Public brief

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodApr 2026–Aug 2026

Design Photo Sharing with Content Deduplication

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Ancestor lookup with upward-only links

Every node in a tree stores only the id of its parent. Given two node ids, find their deepest shared ancestor using those upward links alone.

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Shared ancestor of two nodes in a binary tree

A binary tree arrives in level-order form along with two node values. Identify the lowest node whose subtree contains both values.

New public brief

Topic tags
Python
Data structures

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodAug 2026

Independent Lazy Iterators

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