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Question bank

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.

162 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
Concurrency
Reliability

DatabricksCoding

Talk-through codingNo local grader

Reported interview periodNov 2025–Aug 2026

Durable Multi-Threaded Log Writer

Implement a log writer that accepts binary records from multiple threads and durably appends each complete record to a file.

Practice focusRequirements - Encode each record as a four-byte big-endian length followed by its payload. - push returns only after all bytes for that record are written and the file is synchronized to durable storage. - A record's bytes must never interleave with another record. - Calls from one thread retain program order; calls from different threads may appear in either order. - close must coordinate with active or future pushes and be idempotent. - Handle partial writes, I/O errors, and payload lengths that cannot be represented.…

Public brief

Topic tags
Python
Concurrency

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Hybrid Run-Length and Bit-Packing Codec

Implement a reversible encoder for an integer sequence using run-length blocks for long runs and fixed-size literal blocks otherwise.

Practice focusRequirements and format - A run of at least eight equal values becomes ["RLE", value, count] and consumes the full run. - Otherwise consume the next eight values as ["BP", values] . - A final block may contain fewer than eight values. If every remaining value is equal, encode it as RLE; otherwise use a short BP block. - Walk strictly left to right, making output deterministic. decode must validate the entire block sequence before reconstructing it.…

New public brief

Topic tags
Python
Concurrency
ML / AI

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Build a Tool-Using Research Agent

You are given an LLM client whose responses may contain text blocks or one or more tool-call blocks. Build an agent that answers a user question by repeatedly calling the model, executing requested tools, retur…

Practice focusAssume two tools are available: a stock-price lookup and a shares-outstanding lookup. A question may require one lookup, several independent lookups, or combining results such as market capitalization. Requirements - Preserve the complete conversation history, including assistant tool calls and matching tool results. - Execute every tool call in a response; do not silently discard parallel calls. - Match each result to its tool-call identifier. - Stop only on a final model response, and return its text.…

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
Data structures
Concurrency

OpenAICoding

Python codingWebAssembly + public tests2 versions

Reported interview periodDec 2025–Aug 2026

First-fit heap blocks

Implement a memory allocator over a fixed contiguous address range. Maintain free blocks in a doubly linked list ordered by starting address.

Practice focusallocate(size) must select the first block large enough for the request. Remove an exact-fit block; otherwise advance its start address and reduce its size. Return the allocated start address, or -1 when no block can satisfy the request. free(address, size) returns a region to the free list. Insert it in address order and coalesce it with an adjacent block on the left, right, or both sides when their boundaries touch. Preserve list ordering and links after every operation. Follow-ups 1. Reject overlapping or double frees without corrupting state. 2.…

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
Algorithms
Concurrency
Distributed systems
ML / AI

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodJul 2026–Aug 2026

Debug sharded matrix-multiplication gradients

Implement forward and backward matrix multiplication across world workers.

Practice focusSplit A evenly by rows, replicate B , compute each local A i @ B , and concatenate the local outputs in row order. For the backward pass, compute each local dA i = dY i @ B.T , concatenate the dA i blocks, and compute the global dB as the sum of A i.T @ dY i across workers. Return results that match an unsharded NumPy implementation. Validate matrix shapes and explain the communication required by the forward and backward passes. Follow-ups 1. Shard B instead and compare communication costs. 2. Add uneven row partitions and preserve output ordering. 3.…

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
ML / AI

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Jun 2026

Implement a Longest-Match Tokenizer

Given an input string and a vocabulary, tokenize from left to right using longest-prefix matching.

Practice focusAt each position, emit the integer ID of the longest vocabulary entry matching the remaining text. If nothing matches, emit vocab["UNK"] and advance by one character. With collapse unk=True , collapse consecutive unknown IDs into a single ID; otherwise emit one for each unmatched character. The literal vocabulary entry UNK is reserved and must not match input text as an ordinary token. Assume every token has a distinct integer ID and the vocabulary contains UNK . Requirements and edge cases - Return an empty list for empty input.…

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.…

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.

162 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
Concurrency
Reliability

DatabricksCoding

Talk-through codingNo local grader

Reported interview periodNov 2025–Aug 2026

Durable Multi-Threaded Log Writer

Implement a log writer that accepts binary records from multiple threads and durably appends each complete record to a file.

Public brief

Topic tags
Python
Concurrency

DatabricksCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–Aug 2026

Hybrid Run-Length and Bit-Packing Codec

Implement a reversible encoder for an integer sequence using run-length blocks for long runs and fixed-size literal blocks otherwise.

New public brief

Topic tags
Python
Concurrency
ML / AI

AnthropicCodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Aug 2026

Build a Tool-Using Research Agent

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
Data structures
Concurrency

OpenAICoding

Python codingWebAssembly + public tests2 versions

Reported interview periodDec 2025–Aug 2026

First-fit heap blocks

Implement a memory allocator over a fixed contiguous address range. Maintain free blocks in a doubly linked list ordered by starting address.

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
Algorithms
Concurrency
Distributed systems
ML / AI

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodJul 2026–Aug 2026

Debug sharded matrix-multiplication gradients

Implement forward and backward matrix multiplication across world workers.

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
ML / AI

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodSep 2025–Jun 2026

Implement a Longest-Match Tokenizer

Given an input string and a vocabulary, tokenize from left to right using longest-prefix matching.

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.

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