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.)

(In reply to re: Brute Force by rerun141)

It wasn't deductive logic. It just examined every possible arrangement of fliped and non-flipped switches. That's what we call brute force.

Posted by Charlie on 2003-11-02 20:19:59