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 by )

But unfortunately, doing so would trigger the lights around it because there is only one switch connecting to this light. Furthermore, if you took away its power source you wouldn't be using switches to do it as the problem suggests.

Posted by Gamer on 2003-11-07 07:10:13