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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 161 Coding 161 System design 0 Behavioral 0 Hiring manager 0 Project deep dive 0

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.

142 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

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

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.…

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Pick the longest letter-disjoint word group

Given a list of lowercase words, choose a group in which no letter repeats, either inside a single word or across words, and report the largest total number of letters such a group can contain.

Practice focusRequirements - Line 1 holds the number of words. Line 2 holds exactly that many space-separated lowercase words. - A word may join the group only if all of its own letters are different. - No letter may be shared by two chosen words, so each of the 26 letters appears at most once in the whole group. - Words may be skipped, and selecting no words is allowed. - Maximize the total character count across the chosen words. - Return that maximum as a decimal string, using "0" when no word qualifies.…

Public brief

Topic tags
Python
Algorithms
Data / SQL

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Anagrammed Substring Search

Given a text and a query, find the first position at which a substring of the text is an anagram of the query. Two strings are anagrams when they contain the same characters with the same multiplicities, regard…

Practice focusRequirements Implement: Return the zero-based start index of the first matching window, or -1 when no match exists. An empty query matches at index 0 ; a query longer than the text has no match. Characters are initially compared exactly, including case. Aim for O(n + m) time for a text of length n and query of length m , rather than sorting every window. Additional assessed interfaces 1. Return every matching start index. For an empty query, return every boundary from 0 through len(lookup string) . 2.…

Public brief

Topic tags
Python
Storage & state
Reliability

OpenAICoding

Python codingWebAssembly + public tests2 versions

Reported interview periodNov 2025–Aug 2026

Persist a string map across restart

Implement a durable string-to-string key-value store using the provided FileSystem abstraction.

Practice focusIn the base task, shutdown() commits a complete snapshot using FileSystem.save blob(bytes) . A newly constructed store starts empty; restore() recovers the latest saved snapshot. The supplied storage replaces a whole blob atomically and remains alive across store instances. It models snapshot persistence, not partial writes or a real disk. Keys and values may contain arbitrary Unicode characters, including newlines; use a length-prefixed binary format rather than delimiter-only encoding. Do not use JSON or pickle.…

Public brief

Topic tags
Python
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Turn-Based Creature Battle

Implement a deterministic battle between two teams of creatures. Team A acts first. On each turn, the first living creature on the active team attacks the first living creature on the opposing team.

Practice focusRequirements - Damage reduces health; a creature with health <= 0 is knocked out and cannot act. - Alternate teams after every attack, skipping a side only if it has no living creature—at which point the battle ends. - Log every attack, knockout, and final winner in a deterministic format agreed before coding. - Do not mutate caller-owned teams unless the API explicitly documents it. - Validate empty teams, non-positive attack values, and battles that cannot make progress. Follow-ups 1. Order turns by speed rather than alternating teams. 2.…

New public brief

Topic tags
Python
Data structures

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–Aug 2026

Reconstruct Stack Transitions from Samples and Events

Build utilities for converting between stack observations and call events. Stack frames are ordered outermost to innermost.

Practice focusFor an event stream, push on enter / start , pop on exit / end , record the stack after each event, and run-length encode adjacent identical stacks. For sampled stacks, compare adjacent samples using their longest common prefix. Emit removed frames as end events from innermost outward, then emit added frames as start events from outermost inward. Use the new sample's timestamp and leave frames in the final sample open. Samples have ts and stack fields; events emitted from samples have name , kind ( start or end ) and ts .…

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Leftmost local maximum in a numeric sequence

Given a sequence whose adjacent values never tie, locate the first element that rises above every neighbor it has. Report that element's position.

Practice focusRequirements - The input is one line of space-separated integers with no count prefix, and it holds at least one value. - A position is a local maximum when its value is strictly greater than each neighbor that exists; the first and last positions have only one neighbor. - Return the zero-based index of the earliest such position as a decimal string. - A single-element sequence qualifies at index 0 . - Because neighbors never tie, at least one local maximum always exists and no equality rule is needed.…

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Aug 2026

Count contiguous runs with a target sum

Given an integer array and a target, count the non-empty contiguous runs whose values add up to that target. Values may be zero or negative, so a qualifying run can begin and end anywhere.

Practice focusRequirements - The first line holds the element count and the target, separated by a space; the second line holds the values. - A variant layout puts only the count on the first line, the values on the second, and the target on the third; read the target from whichever position it occupies. - Count every start and end pair, including single elements and runs whose values are all zero. - The empty run never counts, and overlapping runs are counted separately. - Return the count as a decimal string with no other text.…

Public brief

Topic tags
Python
Data structures
Storage & state
Networking

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Follow graph with snapshots

Implement a directed social graph with add_user, follow, and create_snapshot.

Practice focusA snapshot must preserve the follow relationships that existed when it was created. Later mutations to the live graph must not change earlier snapshots. A snapshot supports is following , get following , get followers , and recommend . Self-follows and repeated follows are no-ops. Rank recommendations by the number of two-hop mutual connections in descending order, then by user id in ascending order; return at most k users. Exclude the requesting user and accounts they already follow. Follow-ups 1. Add unfollow while preserving earlier snapshots. 2.…

Public brief

Topic tags
Python
Algorithms
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Aug 2026

Delete a Position from Interval Coverage

A compact coverage set is represented by sorted, non-overlapping, non-touching inclusive intervals. If the covered values were expanded into one ordered sequence, delete the value at a given zero-based position…

Practice focusFor example, [(4, 7), (10, 11), (13, 15)] represents 4,5,6,7,10,11,13,14,15 . Deleting position 2 removes value 6 , producing [[4, 5], [7, 7], [10, 11], [13, 15]] . Requirements - Return intervals as [start, end] pairs. - Preserve sorted, non-overlapping, non-touching output. - A deletion may shrink an endpoint, remove a singleton interval, or split an interval in two. - Assume index refers to an existing covered value; state how you would report an invalid index. - Do not expand every covered integer when ranges may be large.…

New public brief

Topic tags
Python
Data structures
Storage & state

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodApr 2026–Aug 2026

Convert Sampled Call Stacks into Events

A profiler periodically records the active call stack. Convert these snapshots into the minimal sequence of call-start and call-end events.

Practice focusEach sample has an integer timestamp and a stack ordered from outermost to innermost. Each output event contains the sample timestamp, an event type ( start or end ), and a frame name. Rules - Compare each stack with the previous stack using the longest common prefix. - End removed frames from innermost to outermost. - Start added frames from outermost to innermost. - Adjacent identical stacks produce no events. - Equal names at different depths represent different invocations. - Do not invent end events for calls still active in the last sample.…

Public brief

Topic tags
Python
Networking
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Ordered IPv4 Firewall Rules

Implement an ordered firewall policy for IPv4 addresses.

Practice focusEach rule is [action, cidr] , where action is "ALLOW" or "DENY" . Evaluate rules from top to bottom; the first network containing the address determines the result. If no rule matches, deny access. A rule without a prefix length represents one address, equivalent to /32 . Requirements - Parse and validate dotted-decimal IPv4 addresses and CIDR prefix lengths. - Correctly handle /0 , /32 , network boundaries, and overlapping rules. - Preserve first-match semantics; a more specific later rule does not override an earlier match.…

Public brief

Topic tags
Python
ML / AI
Product design

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Implement Batched Scaled Dot-Product Attention

Implement attention for batched multi-head NumPy arrays on CPU. Inputs are finite arrays with the same floating-point dtype; dimensions are positive.

Practice focusShapes are q: (B, H, Tq, Dk) , k: (B, H, Tk, Dk) , and v: (B, H, Tk, Dv) . Return an array of shape (B, H, Tq, Dv) . When return weights=True , return (output, weights) , with weights of shape (B, H, Tq, Tk) . Requirements - Compute scores as q @ k.transpose(-2, -1) / sqrt(Dk) . - Apply softmax along the key-position dimension. - Support an optional boolean mask broadcastable to the score tensor, where false entries cannot receive probability. - Avoid numerical overflow by using a stable softmax or the framework's stable implementation.…

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Aug 2026

Build and Scale an Image-Transformation Pipeline

Given a directory of source images and a directory of transformation specifications, produce one output for every image/specification pair. Each specification contains an ordered sequence selected from grayscal…

Practice focusUse the provided naming callback for every result. Apply transformations in order and save valid output images. Scaling truncates the computed dimensions to integers; rotation expands the canvas. Requirements and edge cases - Discover supported image and specification files recursively or according to the supplied listing helper. - Do not share mutable image objects across independent pipelines. - Ensure all scheduled work completes before returning and propagate worker failures.…

Public brief

Topic tags
Python
Data structures

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodSep 2025–Aug 2026

Find Duplicate Files Efficiently

Walk a directory tree and return groups of files whose complete byte contents are identical.

Practice focusEach returned path must be absolute and resolved. Omit groups containing only one file. Group and path order are not significant. Requirements - Skip symbolic links and continue past files that become unreadable. - Treat multiple empty files as duplicates. - Avoid reading every byte of every file when cheap evidence can rule out equality. - A full-content comparison or collision-resistant digest must confirm every reported group. - Stream large files in bounded-size blocks rather than loading them entirely into memory.…

Public brief

Topic tags
Python
Data structures
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Iterator that can pause and resume

Implement ResumableListIterator, an iterator that can save and restore its progress.

Practice focusget state() must return a JSON-serializable value that fully identifies the next item to produce. set state(state) must restore that position so iteration continues without repeating or skipping values. The iterator should use constant additional memory and follow normal Python iterator behavior at end of input. Handle empty and single-item lists, restoration at the beginning and end, invalid state, and repeated save/restore cycles. Follow-ups 1. Extend the design to a nested iterator. 2. Detect restoration against a changed underlying collection. 3.…

Public brief

Topic tags
Python
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Aug 2026

Online softmax entropy

Implement numerically stable softmax, log-softmax, and entropy for a vector of logits. The standard entropy is -Σ p log p.

Practice focusThen implement a block-wise variant that processes the logits in bounded-size chunks without losing numerical stability. The block-wise result must match the full-vector computation within floating-point tolerance. Handle very large and very small logits, empty inputs according to the provided contract, and both supported entropy-sign conventions. Explain why subtracting the maximum logit prevents overflow and how partial statistics combine across blocks. Follow-ups 1. Return gradients with respect to the logits. 2.…

Public brief

Topic tags
Python
Data structures
Reliability

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodOct 2025–Jul 2026

Make an LRU Function Cache Crash-Recoverable

Complete an LRU cache that memoizes arbitrary function calls and survives process restart using an append-only write-ahead log.

Practice focusRequirements - Keys must include function identity and recursively canonicalized arguments. - Keyword insertion order must not affect identity; nested lists and dictionaries must be supported. - Hits return the stored value without executing the function and become most-recently used. - Append a complete record for every access before returning, so replay reconstructs values and recency. - Enforce capacity during both live operation and replay.…

New public brief

Topic tags
Python

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Decode a Nested String

An encoded string uses the form k[segment], meaning that segment is repeated k times. Repeat counts are positive and may contain multiple digits. Encoded segments may be nested, while ordinary characters are co…

Practice focusImplement: Examples: - 3[a]2[bc] becomes aaabcbc . - 3[a2[c]] becomes accaccacc . - 2[abc]3[cd]ef becomes abcabccdcdcdef . Assume the input is syntactically valid. Avoid recursion-depth dependence by using an explicit stack. The running time should be proportional to the encoded input plus the produced output. Staged follow-ups 1. Validate malformed input and report the location of the first syntax error. 2. Support a postfix form such as (segment){k} and escaped delimiter characters. 3.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Column order of a binary tree

Rebuild a binary tree from its level-order serialization, then group the node values by column, moving left to right across columns. Inside one column the values should follow the order in which a breadth-first…

Practice focusRequirements - The first line is a level-order serialization separated by commas. A missing child is written as null , and the whole line may optionally be wrapped in square brackets. An empty line or [] means there is no tree. - Children attach in queue order: each non-null node consumes the next two slots as its left child and then its right child. - The root sits in column 0; a left edge shifts the column by -1 and a right edge by +1 . - Emit one inner list per occupied column, ordered from the smallest column offset to the largest.…

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Jul 2026

Build a Temporal In-Memory Database with Backup and Restore

Process timestamped commands over records that map string keys to string field/value pairs. Timestamps are unique and strictly increasing; each command returns one string.

Practice focusCommand contract Every command is a list of strings. t , ttl and target are decimal integer strings. Command timestamps t are nonnegative and strictly increasing across the entire input; ttl is positive. Keys and field names are nonempty strings. Values may be empty strings. Inputs contain only the commands below with the stated argument counts. Return one output string for each input command, in order. | Command | Output | | --- | --- | | ["SET", t, key, field, value] | "" ; replace the field with a permanent value.…

Previous4 of 6Next

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 161 Coding 161 System design 0 Behavioral 0 Hiring manager 0 Project deep dive 0

Topics

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

142 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

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

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

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Pick the longest letter-disjoint word group

Given a list of lowercase words, choose a group in which no letter repeats, either inside a single word or across words, and report the largest total number of letters such a group can contain.

Public brief

Topic tags
Python
Algorithms
Data / SQL

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Anagrammed Substring Search

Public brief

Topic tags
Python
Storage & state
Reliability

OpenAICoding

Python codingWebAssembly + public tests2 versions

Reported interview periodNov 2025–Aug 2026

Persist a string map across restart

Implement a durable string-to-string key-value store using the provided FileSystem abstraction.

Public brief

Topic tags
Python
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Turn-Based Creature Battle

Implement a deterministic battle between two teams of creatures. Team A acts first. On each turn, the first living creature on the active team attacks the first living creature on the opposing team.

New public brief

Topic tags
Python
Data structures

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–Aug 2026

Reconstruct Stack Transitions from Samples and Events

Build utilities for converting between stack observations and call events. Stack frames are ordered outermost to innermost.

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Leftmost local maximum in a numeric sequence

Given a sequence whose adjacent values never tie, locate the first element that rises above every neighbor it has. Report that element's position.

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodMar 2026–Aug 2026

Count contiguous runs with a target sum

Given an integer array and a target, count the non-empty contiguous runs whose values add up to that target. Values may be zero or negative, so a qualifying run can begin and end anywhere.

Public brief

Topic tags
Python
Data structures
Storage & state
Networking

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Follow graph with snapshots

Implement a directed social graph with add_user, follow, and create_snapshot.

Public brief

Topic tags
Python
Algorithms
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Aug 2026

Delete a Position from Interval Coverage

New public brief

Topic tags
Python
Data structures
Storage & state

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodApr 2026–Aug 2026

Convert Sampled Call Stacks into Events

A profiler periodically records the active call stack. Convert these snapshots into the minimal sequence of call-start and call-end events.

Public brief

Topic tags
Python
Networking
Security

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Ordered IPv4 Firewall Rules

Implement an ordered firewall policy for IPv4 addresses.

Public brief

Topic tags
Python
ML / AI
Product design

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Implement Batched Scaled Dot-Product Attention

Implement attention for batched multi-head NumPy arrays on CPU. Inputs are finite arrays with the same floating-point dtype; dimensions are positive.

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Aug 2026

Build and Scale an Image-Transformation Pipeline

Public brief

Topic tags
Python
Data structures

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodSep 2025–Aug 2026

Find Duplicate Files Efficiently

Walk a directory tree and return groups of files whose complete byte contents are identical.

Public brief

Topic tags
Python
Data structures
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Iterator that can pause and resume

Implement ResumableListIterator, an iterator that can save and restore its progress.

Public brief

Topic tags
Python
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026–Aug 2026

Online softmax entropy

Implement numerically stable softmax, log-softmax, and entropy for a vector of logits. The standard entropy is -Σ p log p.

Public brief

Topic tags
Python
Data structures
Reliability

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodOct 2025–Jul 2026

Make an LRU Function Cache Crash-Recoverable

Complete an LRU cache that memoizes arbitrary function calls and survives process restart using an append-only write-ahead log.

New public brief

Topic tags
Python

GoogleCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Decode a Nested String

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Column order of a binary tree

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–Jul 2026

Build a Temporal In-Memory Database with Backup and Restore

Process timestamped commands over records that map string keys to string field/value pairs. Timestamps are unique and strictly increasing; each command returns one string.

Previous4 of 6Next

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