Scale Software Engineer
Interview Guide

Implement a custom card game (e.g., Poker or Go Fish) given base Card, Deck, and Player classes. Handle dealing, hand sorting by suit/rank, multi-player turns, and score evaluation.

Build a game loop for a grid-based cellular automaton (such as a Game of Life or neuron-firing variant) where cell states update based on neighboring cell conditions. Optimize state updates for memory efficiency.

Construct a string reordering utility that sorts characters based on target frequency constraints and custom layout criteria within tight time limits.

Extend a task scheduler to enforce task-to-subtask dependencies, worker thread capability constraints, and specific step-by-step execution ordering.

Parse a stream of time-interval data to compute overlapping party windows, dead-zone hours across geographic locations, and aggregate activity durations.

Implement a task queue service with support for task addition, dependency resolution (e.g., topological sorting), and execution deadlines.

Parse and transform nested JSON payload structures containing geographic and operational state data to compute target summary metrics.

Write a recursive utility function to flatten deeply nested, arbitrary data structures containing mixed scalar and list primitives.

resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.

A tenant on the standard plan may hold at most 50 resources with status='active'. The create handler runs SELECT count(*) FROM resource WHERE tenant_id = $1 AND status = 'active', compares to 50, then inserts. Two creates arrive 3 ms apart on different instances and the tenant lands at 51. Name the anomaly, say whether PostgreSQL 16 READ COMMITTED or REPEATABLE READ prevents it and why, then give an implementation that holds the cap at READ COMMITTED with the exact statements. Finally, say what changes when the cap is 'at most one running export per tenant' on job_run.

Extend a poker evaluation engine to support wildcard rules, such as dynamic Joker handling, and detect specific hand combinations under strict constraints.

Design and implement a task scheduler service capable of assigning tasks to available execution threads, outputting chronological step logs.

Build a location-routing service that interfaces with external places and routing APIs to fetch locations, compute pairwise travel times, and solve a Traveling Salesperson Problem (TSP) to minimize travel time.

Architect a real-time data ingestion and labeling pipeline capable of handling high-volume continuous data streams with strict SLA requirements.

Design a high-throughput, low-latency task distribution network for routing human annotation jobs to concurrent global workers.

Walk through the architecture of a complex end-to-end backend system you previously built, explaining trade-offs regarding scalability, database selection, and fault tolerance.

Debug an existing multi-file codebase (e.g., an automated task or project assignment engine) to identify subtle edge-case failures, such as state un-reset inside nested loops or incorrect sorting criteria.

Troubleshoot and fix broken test suites in a Python or Node.js web application framework, identifying middleware bugs or incorrect routing logic.