The textbook warm-up that tests for the hash-map instinct: swap space for time to turn O(n squared) into O(n). Interviewers look for the one-pass complement lookup. The pattern follows.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
The textbook warm-up that tests for the hash-map instinct: swap space for time to turn O(n squared) into O(n). Interviewers look for the one-pass complement lookup. The pattern follows.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
