This grid of numbers is WormWorld, and it's a tough place to live. The worms that inhabit it are all born with nasty allergies. The first time they come in contact with a number, their immune systems are overstimulated; if they are exposed to that number a second time, they die of anaphylactic shock.
A worm can start crawling on any square in WormWorld, and it can then move horizontally or vertically but not diagonally. What is the longest path a worm can take without dying?
My WormWorld puzzle was first published in the November 1994 issue of Discover Magazine, and is reprinted here with permission of the publisher. I publish 8 "Brain-Bogglers" every year in Discover. Additional information on WormWorld will appear in my book KEYS TO INFINITY, published in the Fall of 1995 by Wiley. This describes the Internet WormWorld Tournament I held, inviting people to compete against a computer program.
Back to
Cliff Pickover's home page