Puzzles

Questions I've been asked in interviews
Since I still think these are nifty potential interview questions (and because I'm naturally lazy), I'm not planning to post answers to these questions here anytime soon. If you're stumped, feel free to send me mail. But don't expect me to hire you ;-). Why are manhole covers round? (Apple, 1989) Can you do arithmetic base -2? (Microsoft, 1989) What's a quick way to count the number of 'on' bits in a bit string of length n? (Microsoft, 1989) How many (topologically) different ways are there to arrange a pair of circles in the plane? (Parametric Technology, 1995)
Questions I've heard rumored to be asked in interviews
The U2 Puzzle
Questions I've heard debated with surprising vehemence
The significant digit phenomenon The Monty Hall problem
Questions which puzzle me to this day
What is the topology of the configuration space of the tangle toy? How do you construct a good set of coordinates for the configuration space of a planar linkage? How do you pick a viewing angle for projecting a finite collection of points in Euclidean n-space down onto Euclidean m-space so as to maximize the smallest distance between their projected images? My dice loading problem. Bar Natan's problem.

Last updated on May 3, 2001 by Peter Wolfenden.
Wolfenden's Homepage.