Currently-available coding interview challenges.
Thread-Safe LRU Cachecpp-lru-cache
Make an existing LRU cache implementation thread-safe and fix planted bugs in eviction and edge-case handling. Get/put must remain O(1).
Streaming Metrics Aggregatorcpp-wafer-telemetry
Fix concurrency and numerical-stability bugs in a streaming per-source/per-sensor stats aggregator, wire SPC excursion detection through, implement a wafer-lifecycle finaliser, and design a batched async excursion reporter from scratch.
Thread-Safe TTL Cachepython-ttl-cache
Make an existing TTL cache implementation thread-safe, enforce TTL expiry on reads, and fix planted bugs in eviction and edge-case handling. Get/put must remain amortised O(1).
Per-Key Token-Bucket Rate Limitertypescript-rate-limiter
Make a per-key token-bucket rate limiter correct under refill, validate constructor inputs, cap tokens at capacity after long idle, and ensure acquire() never hangs forever when the bucket cannot refill. The starter compiles and passes simple happy-path cases but contains planted bugs in refill math, input validation, and the async slow path.