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Encode and Decode Strings
This is a string problem that rewards careful parsing and strong edge-case instincts. Interviewers love it because it reveals your rule-based parsing and your edge-case discipline. Go slow on indexing; most string bugs are just off-by-one mistakes.
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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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