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Detect Squares
Detect Squares is a classic scan-and-record problem: the right bookkeeping beats brute force. Interviewers love it because it reveals your data-structure instincts and your edge-case discipline. The classic trap is mishandling duplicates or overwriting useful information too early.
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Low-Level Design Interview Questions
Low-level design problems test whether you can model a small API, preserve invariants, and choose storage that matches the required operations. Expect recurring shapes like rate limiters, hit counters, tic-tac-toe, file systems, and autocomplete.
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