{"blocks": [{"key": "a8378d34", "text": "Scenario", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "524a7ca9", "text": "You are asked to build a data-driven advertising platform that serves personalized ads to millions of users in real time.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "abdd09cd", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "0c39538d", "text": "Design an end-to-end machine-learning system for ad selection: discuss data collection, labeling, feature engineering, model choice, exploration-exploitation strategy, online/offline evaluation, latency constraints, and scalability.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "8e1ff109", "text": "Hints", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "97a52f66", "text": "CTR prediction with logistic regression/GBDT, counterfactual evaluation, feature store, bandits for exploration.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}