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Design Add and Search Words Data Structure
This is really about exploring a state space without revisiting the same work. Interviewers love it because it reveals your traversal modeling and your edge-case discipline. Be clear about what a state is; that's the difference between BFS/DFS working or blowing up.
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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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