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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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Frontier Rehearsal · Independent practice · Not affiliated with OpenAI, Anthropic, or xAI.

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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 162 Python 161 Algorithms 36 Data structures 36 Concurrency 19 Distributed systems 7 Storage & state 23 Networking 6 Reliability 9 ML / AI 12 Data / SQL 17 Security 4 Product design 9 Communication 5

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

150 questions

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

Coding results

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

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.…

Public brief

Topic tags
Python

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodJun 2026–Jul 2026

Repair a Looping Instruction Program

A small virtual machine executes a list of instructions over one integer accumulator. Blank lines and comment lines are ignored.

Practice focus- plus n : add n to the accumulator and move to the next instruction. - next n : ignore n and move to the next instruction. - jump n : move to the instruction at current index + n . Execution halts when the program counter moves outside the instruction list. It loops when it is about to execute an instruction that has already run. Exactly one jump or next instruction was swapped while keeping its operand. Interface Return -1 from the first two functions if the original program already halts.…

Public brief

Topic tags
Python
Product design

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Infer return types in a tiny generic type system

Implement type substitution for a small language. Types are either atomic names, such as int or generic T, or product types containing an ordered list of child types. A function describes parameter templates an…

Practice focusScenario Implement type substitution for a small language. Types are either atomic names, such as int or generic T , or product types containing an ordered list of child types. A function describes parameter templates and an output-type template. Given concrete argument types, infer the concrete return type. Treat int , float , str , bool , and char as concrete primitives. Any other atomic name in a function template is a generic variable.…

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2025–Jul 2026

Build a Bank Ledger with Held Transfers and Account Merges

Implement an in-memory banking service whose operations arrive in nondecreasing timestamp order.

Practice focusRequirements - Account creation starts at zero and returns True , or False if that identifier is already active. Deposits and withdrawals return the total balance, including held funds; invalid accounts or invalid amounts return None . A zero deposit is a read of the current balance. Negative deposits, and zero or negative withdrawals and transfers, are invalid. - Starting a transfer requires both accounts to exist and available funds (total balance minus holds) to cover the amount.…

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJun 2026

Shortest distinguishing prefix per word

Given a list of distinct lowercase words, return for each word the shortest opening slice that no other word in the list also starts with, preserving input order.

Practice focusRequirements - The first input line is the word count n ; the next n lines each hold one lowercase word. - Emit one prefix per line in input order, joined by newlines, with no summary line and no trailing separator. - Each prefix must be a leading slice of its own word and must not be a leading slice of any other word in the list. - Prefer the shortest qualifying slice: extend the prefix only until the character that no other word shares at that depth. - A list holding a single word uses that word's first character.…

Public brief

Topic tags
Python
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Jun 2026

Implement a Versioned Recipe Manager

Build an in-memory recipe service with unique names, search, users, and rollback.

Practice focusRecipe IDs and names are unique; name comparison and search are case-insensitive while original casing is preserved. Returned recipes must be defensive copies. Search results sort by ingredient count and then recipe ID. Successful adds and edits append immutable, one-based versions. IDs and names are nonempty strings; ingredients are lists of strings, preserving order and repetitions. Name uniqueness and substring search compare Python-style lowercase strings, without trimming or accent normalization. An empty search query matches every recipe.…

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Jun 2026

Implement a Same-Host Web Crawler

You are given a seed URL and a parser object. Calling htmlParser.getUrls(url) returns the links found on that page. Return every reachable URL whose hostname matches the seed URL's hostname, including the seed …

Practice focusRequirements - Visit each accepted URL at most once. - Never follow a link to another hostname. - Use the supplied parser rather than implementing HTTP fetching. - Return all reachable accepted URLs; result order is not significant. - Treat complete URL strings as visit identities. Compare parsed hostnames, not hostname substrings; different ports and schemes on the same hostname remain eligible. Assume syntactically valid absolute HTTP(S) URLs. No URL canonicalization, redirect fetching or network access is required.…

Public brief

Topic tags
Python
Data structures
Reliability

AnthropicCodingHalf AI-generated

Talk-through codingNo local grader

Reported interview periodOct 2025–Jun 2026

Design a Type-Safe Durable LRU Cache

Extend a crash-recoverable LRU cache to support built-in containers and explicitly registered domain objects without using unsafe object serialization.

Practice focusRequirements - Produce canonical, type-tagged keys for None , booleans, integers, finite floats, strings, bytes, lists, tuples, dictionaries, sets, frozensets, and registered objects. - Preserve distinctions such as True , 1 , and 1.0 ; make dictionary and set identity independent of iteration order. - Allowlist exact classes through unique stable tags. Never dynamically import a class named by stored data. - Encode and decode cached values through the registry and reject unknown or malformed tags.…

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–May 2026

Implement a Quota-Aware Cloud File Store

Process a sequence of string commands against a flat cloud-storage namespace. Every command returns one result string.

Practice focusOperations - Add a file with a unique name and integer size; copy an existing file to a free name; query a file's size. - Find files matching both a prefix and suffix, sorted by size descending and then name ascending. - Add quota-limited users and add user-owned files only when capacity permits. - Reduce a user's capacity, evicting that user's largest files first and using name order to break ties until usage fits. - Compress an owned file by renaming it with a .COMPRESSED suffix and halving its even size.…

Public brief

Topic tags
Python
Storage & state
Networking

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a DNS Resolver with Aliases and TTL

Build an in-memory resolver over A and CNAME records.

Practice focusRequirements - Normalize domain names case-insensitively and ignore a trailing dot. - An A record resolves directly to its address while live. - A CNAME follows its target recursively until a live A record is found. - Each record has type ( A or CNAME ) and value (address or target). Optional ttl is a duration; set at defaults to zero. A missing or null ttl means no expiration. - A record expires when now = set at + ttl . - Any expired or missing link makes resolution fail.…

Public brief

Topic tags
Python
Storage & state
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a Task Manager with Expiration and Historical Views

Tasks are scoped by (user, task_id). Implement creation, mutation, TTL expiration, and snapshots.

Practice focusRequirements - A task key can be created only once, even if the task later completes or expires. - Only live incomplete tasks can be updated or completed. - TTL is anchored at creation; a task is absent at and after created at + ttl , and updates do not refresh it. - Current lists contain live incomplete titles ordered by task ID. - A historical list includes all events at or before the requested timestamp and applies expiration relative to that historical time. - Calls arrive in nondecreasing command time, though historical query times may be earlier.…

Public brief

Topic tags
Python
Data structures
Data / SQL

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–May 2026

Design a Weighted, Checkpointable Data Batcher

You are training on several named datasets. A registry can open an iterator for a dataset at a supplied item offset. Design a batcher that mixes examples according to positive integer weights and can resume exa…

Practice focusThe supplied registry exposes get iterator(name, offset=0) , returning an iterator beginning at that dataset's zero-based item offset. It does not advance any other dataset. Implement the batcher, not the registry. Requirements - Every full batch contains exactly batch size examples while data remains available. - Allocate the integral share first, then distribute leftover slots using a deterministic largest-remainder carry across batches. - Break ties by the insertion order of weights and emit examples grouped in that same dataset order.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–May 2026

Kth largest value with duplicates counted

Return the k-th value in descending order from an integer array, treating equal values as separate entries. The input arrives in one of two line layouts.

Practice focusRequirements - Layout A: line one is the element count, line two holds the integers, and line three is k . - Layout B: line one is nums=[3,2,1,5,6,4] and line two is k=2 , with no space before either equals sign. - k is one-based and always lies between 1 and the array length, so k = 1 asks for the maximum and k equal to the length asks for the minimum. - Return the selected value as a decimal string; it is a value, not a position.…

Public brief

Topic tags
Python
Concurrency
Distributed systems
Storage & state
Data / SQL

AnthropicCodingHalf AI-generated

Talk-through codingNo local grader

Reported interview periodOct 2025–May 2026

Design Worker and Coordinator Protocols for Distributed Statistics

You control N workers and one coordinator. Worker i can read only shard i. Endpoints communicate by messages; there is no shared mutable dataset. Sending captures an independent snapshot of the payload; later s…

Practice focusThe task is either mode or median . For mode, return the globally most frequent integer with the smaller value winning ties. For median, return the exact middle value as a float, or the mean of the two middle values for even cardinality. The global input is non-empty; individual shards may be empty. Requirements - Define message shapes and an explicit completion condition. - Do not assume the coordinator can read worker data directly. - Avoid shipping complete raw shards in the scalable solution.…

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Fewest inserts to balance brackets

Report how many bracket characters must be inserted anywhere in a parenthesis string to make every prefix and the whole line balanced.

Practice focusRequirements - The input is one line containing only ( and ) . - A string is balanced when every prefix has at least as many ( as ) , and the total counts are equal. - Insertions may be placed at any position. Removing, replacing, or reordering characters is not allowed. - Return the minimum number of inserted characters as a decimal string. - A line that is already balanced returns "0" . - 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 periodApr 2026

Tightest slice covering a character multiset

Find the shortest contiguous slice of a source string that contains every character of a required multiset with at least the required multiplicity, and return that slice.

Practice focusRequirements - Line 1 is the source string. Line 2 lists the required characters. - The chosen slice must be contiguous and must contain each required character at least as many times as it appears on line 2. - Compare slices by length. When several slices tie for the shortest length, return the one that begins earliest. - If no slice qualifies, return an empty string. - Matching is case-sensitive. - Return the slice itself, not its length and not its bounds. - run case(case: dict) forwards case["stdin"] to solve .…

New public brief

Topic tags
Python
Concurrency

xAICoding

Talk-through codingNo local grader

Reported interview periodNov 2025–Apr 2026

Make a Bank Account Thread-Safe

You are given a BankAccount whose deposit method performs a read-modify-write operation and may pause between reading and writing. You cannot modify that class. Implement a subclass that makes deposits safe whe…

Practice focusCall the inherited implementation rather than copying it. Two deposits of 500 and 700 into an account starting at 0 must finish with 1200 . Ensure the lock is released if the inherited method raises. The supplied constructor creates the account and its lock. Complete deposit only. The provided run case adapter owns the concurrent fixture execution; it is not candidate work. Opening balances and deposit amounts are integers, and deposit amounts are nonnegative. Empty deposit lists leave the opening balance unchanged. Each successful call returns None .…

Previous5 of 7Next

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.

150 questions

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

Coding results

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

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.

Public brief

Topic tags
Python

AnthropicCoding

Talk-through codingNo local grader

Reported interview periodJun 2026–Jul 2026

Repair a Looping Instruction Program

A small virtual machine executes a list of instructions over one integer accumulator. Blank lines and comment lines are ignored.

Public brief

Topic tags
Python
Product design

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Infer return types in a tiny generic type system

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2025–Jul 2026

Build a Bank Ledger with Held Transfers and Account Merges

Implement an in-memory banking service whose operations arrive in nondecreasing timestamp order.

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJun 2026

Shortest distinguishing prefix per word

Given a list of distinct lowercase words, return for each word the shortest opening slice that no other word in the list also starts with, preserving input order.

Public brief

Topic tags
Python
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Jun 2026

Implement a Versioned Recipe Manager

Build an in-memory recipe service with unique names, search, users, and rollback.

Public brief

Topic tags
Python

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Jun 2026

Implement a Same-Host Web Crawler

Public brief

Topic tags
Python
Data structures
Reliability

AnthropicCodingHalf AI-generated

Talk-through codingNo local grader

Reported interview periodOct 2025–Jun 2026

Design a Type-Safe Durable LRU Cache

Extend a crash-recoverable LRU cache to support built-in containers and explicitly registered domain objects without using unsafe object serialization.

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–May 2026

Implement a Quota-Aware Cloud File Store

Process a sequence of string commands against a flat cloud-storage namespace. Every command returns one result string.

Public brief

Topic tags
Python
Storage & state
Networking

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a DNS Resolver with Aliases and TTL

Build an in-memory resolver over A and CNAME records.

Public brief

Topic tags
Python
Storage & state
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a Task Manager with Expiration and Historical Views

Tasks are scoped by (user, task_id). Implement creation, mutation, TTL expiration, and snapshots.

Public brief

Topic tags
Python
Data structures
Data / SQL

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025–May 2026

Design a Weighted, Checkpointable Data Batcher

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–May 2026

Kth largest value with duplicates counted

Return the k-th value in descending order from an integer array, treating equal values as separate entries. The input arrives in one of two line layouts.

Public brief

Topic tags
Python
Concurrency
Distributed systems
Storage & state
Data / SQL

AnthropicCodingHalf AI-generated

Talk-through codingNo local grader

Reported interview periodOct 2025–May 2026

Design Worker and Coordinator Protocols for Distributed Statistics

Public brief

Topic tags
Python

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Fewest inserts to balance brackets

Report how many bracket characters must be inserted anywhere in a parenthesis string to make every prefix and the whole line balanced.

Public brief

Topic tags
Python
Algorithms

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Tightest slice covering a character multiset

Find the shortest contiguous slice of a source string that contains every character of a required multiset with at least the required multiplicity, and return that slice.

New public brief

Topic tags
Python
Concurrency

xAICoding

Talk-through codingNo local grader

Reported interview periodNov 2025–Apr 2026

Make a Bank Account Thread-Safe

Previous5 of 7Next

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