Sign In

Communications of the ACM

Last byte

Stay in Balance

blocks on teeter totter

Credit: Getty Images

Two players, each with a collection of weights, sit in front of a plank that weighs three kilograms with two supports at −1 and +1. Each player wants to get rid of his or her weights, by placing them on integral markers, at most one weight per integral marker. So, for example, player A may not place a weight above A's weights or player B's weights. Further, neither player is allowed to place a weight at −1, 0, or +1.

In a turn, a player must put at least one weight somewhere on the plank, but may put several weights on the plank, if they are at consecutive integer marks. The goal of each player is to be the first to place all of his or her weights without causing the plank to tip (by having a strictly negative torque on the right support or a strictly positive torque on the left support).


No entries found

Log in to Read the Full Article

Sign In

Sign in using your ACM Web Account username and password to access premium content if you are an ACM member, Communications subscriber or Digital Library subscriber.

Need Access?

Please select one of the options below for access to premium content and features.

Create a Web Account

If you are already an ACM member, Communications subscriber, or Digital Library subscriber, please set up a web account to access premium content on this site.

Join the ACM

Become a member to take full advantage of ACM's outstanding computing information resources, networking opportunities, and other benefits.

Subscribe to Communications of the ACM Magazine

Get full access to 50+ years of CACM content and receive the print version of the magazine monthly.

Purchase the Article

Non-members can purchase this article or a copy of the magazine in which it appears.
Sign In for Full Access
» Forgot Password? » Create an ACM Web Account