System design interview question
"Design an online auction site. Sellers list items with a deadline; buyers bid; the highest bid at the deadline wins. The interesting part is the last few seconds — a popular auction gets hundreds of bids in the final ten seconds, and the outcome must be correct and defensible."
correctness under a deadline with a contention spike, plus a bidding model most candidates get wrong. Two distinctive parts: proxy bidding (the displayed price is not what the bidder entered), and sniping, which produces an extreme burst exactly at the moment correctness matters most.
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