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Brainteasers & Logic
Deduction, information theory, and Fermi estimation.
Prerequisites: None (entry point)
- 1Weighing and DeductionA balance has three outcomes, so k weighings separate at most 3ᵏ cases: count the cases first, then design each weighing so every branch still fits.
- 2Knowledge Puzzles: Hats and Cheryl's BirthdayTreat every statement as a filter on the worlds a player cannot rule out, and hat lines, Cheryl's birthday and the blue-eyed islanders all come apart the same way.
- 3Game Theory Puzzles: Pirates, Nim and Backward InductionSolve a game from its last move backwards: the race to 100, the pirate game, the XOR rule for Nim, and the mirror strategy.
- 4Fermi Estimation and Mental MathTo estimate a number like the count of barbers in New York, split it into factors you can guess, give a range, and do the arithmetic in your head fast enough that the interviewer keeps listening.
Practice
The problem bank has 31 interview problems on this material, with hints and full solutions.
Practice 31 related problems