Explanations built around an animation you can step through.
An ordered route through the algorithms, with practice by pattern.
Design practice, capacity sizing, and a regex safety check.
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All 188 →A hot cache key expires, thousands of requests miss at once, and all of them run the same expensive query. How cache stampedes happen, and the fixes: request coalescing, a rebuild lock, serving stale data while revalidating, probabilistic early expiration, and TTL jitter.
The most common low-level design interview question, worked end to end: clarifying requirements, finding the entities, choosing composition over inheritance, putting spot allocation and pricing behind strategies, handling concurrent arrivals, and the code for the core flow.
Why LIKE '%term%' doesn't scale, and what search engines do instead. Tokenising and normalising text, postings lists with positions, fast AND, OR and phrase queries, ranking with BM25, and how Lucene-style engines keep the index updated with immutable segments.
Why setInterval animations stutter, how requestAnimationFrame syncs your code with the display's refresh, why movement should depend on elapsed time rather than frame count, what to animate so the browser can skip layout, and when CSS or the Web Animations API is the better tool.