Imagine there is a 5x5 grid of lights, and only the middle light in the grid is on.

The lights are wired such that when you flip the switch for one light (from on to off or off to on) the others right next to it (not diagonally) flip as well.

Using this weird wiring of lights, what is the fewest number of switch changes it takes to turn all the lights off, and which lights should you switch? (Assume all the switches work in the manner explained, and there is 1 switch for each of the lights.)

The point of this problem is to either give a way that its possible, or prove that it's impossible. I don't have a solution to this, but I have been wondering and thought it would be a good problem for others.

The answer it to turn them all off, not on. :)

Posted by Gamer on 2003-11-02 11:00:45