Problem: The king has 500 barrels of wine, but one of them is poisoned. Anyone drinking the poisoned wine will die within 12 hours. The king has four prisoners whom he is willing to sacrifice in order to find the poisoned barrel. Can this be done within 48 hours?
King's Poisonous Wine Puzzle - CSE Blog
Solution posted by Tejas Hiremani (IITB EE Alumnus, Goldman Sachs Quant), Siddhant Agarwal (IITB EE Senior Undergraduate), Mehul Tikekar (IITB EE Alumnus, MIT PhD Candidate) and Gaurav Sinha (chera, IITK 1996 Graduate, Indian Revenue Service) in comments!