Design a 'People You May Know' (friend/connection recommendation) system.
PYMK is graph recommendation at billion-node scale. The interviewer is testing for one instinct: do you generate candidates from the social graph, or naively try to score every pair? Here is the design that holds up through the follow-ups.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
PYMK is graph recommendation at billion-node scale. The interviewer is testing for one instinct: do you generate candidates from the social graph, or naively try to score every pair? Here is the design that holds up through the follow-ups.
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.
