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phone interview with their search/machine learning/recommender system team. Interview around 1 hour and interviewer is from Korean.|
coding: there are K files with time stamped log information, how to merge them into one big file based on time sequence order. The question is similar to merge K sorted list but should handle how to read 10 files at the same time.
design: write a pseudo code to design a recommendation system engine. I use matrix factorization based model with stochastic gradient descent optimization for parameter learning.