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GPU Credits Manager
Build a GPU credit ledger where events arrive out-of-order. Grants expire, subtracts allocate FEFO (soonest-expiring-first), and queries ask for balance at any timestamp. Part 2 adds retroactive cancellations, forcing full replay correctness.
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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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