Frontier AI Technical Interview Question Bank

Topic tags
Python
Storage & state

Reported interview periodDec 2025–Apr 2026

In-Memory Database with Expiry and Snapshots

Build an in-memory database in four stages. Each key owns string field/value pairs.

Practice focusMissing values return "" . Scans emit field(value) entries sorted by field. A TTL value is live over [created at, created at + ttl) . A backup captures all live fields and each field's remaining lifetime. Restore selects the newest backup at or before timestamp to restore , replaces current state, and restarts remaining lifetimes at timestamp . Assume timestamps supplied to mutating timed operations are nondecreasing. Backups must not share mutable state with the live database.…

New public brief

Topic tags
Python
Data structures
Storage & state
Networking

xAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Token-Bucket State Transitions

Each subject has a token bucket stored in a shared key-value cache. A missing bucket begins full. Refill lazily when a request arrives: add elapsed_time * refill_rate, capped at capacity. If time has not advanc…

Practice focusAccept only when the refilled balance covers the full request, then subtract it. A rejected request spends nothing. Persist the refilled state in either case. A backward-moving clock must not create tokens. TokenBucket and the in-memory DistributedCache test double are provided. This base task is sequential; the cache name does not imply atomic distributed behavior. Refill returns a new bucket without editing its argument. Existing buckets retain their stored capacity/refill rate; call configuration initializes missing buckets only.…

Public brief

Topic tags
Python
Algorithms
Data structures
Storage & state
Networking

Coding exerciseCodingAI-generated

Runnable coding45 min

Reported interview periodN/A

Sliding-window rate limiter

Build a limiter, then add quota reporting, retry timing, and independent keys.

Practice focusPython, Queues, State, Boundary cases, Complexity through a runnable coding exercise.

Public brief

Topic tags
Python
Storage & state

Coding exerciseCodingAI-generated

Runnable coding45 min

Reported interview periodN/A

Command-log store

Evolve a tiny state machine through undo, compaction, and snapshot replay.

Practice focusPython, State machines, Undo logs, Compaction, Persistence through a runnable coding exercise.

Public brief

Topic tags
Python
Data structures
Storage & state

Coding exerciseCodingAI-generated

Runnable coding50 min

Reported interview periodN/A

Streaming metric window

Compute ordered rolling metrics, then partition state and expose freshness explicitly.

Practice focusPython, Queues, Streaming state, Boundaries, Observability through a runnable coding exercise.

Frontier AI technical interview question bank.

Frontier AI technical interview question bank.

In-Memory Database with Expiry and Snapshots

Token-Bucket State Transitions

Sliding-window rate limiter

Command-log store

Streaming metric window

In-Memory Database with Expiry and Snapshots

Token-Bucket State Transitions

Sliding-window rate limiter

Command-log store

Streaming metric window