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Lights Out! (Posted on 2003-11-02) Difficulty: 4 of 5
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.)

See The Solution Submitted by Gamer    
Rating: 4.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution re: Brute Force | Comment 15 of 26 |
(In reply to Brute Force by Charlie)

Oh, yes, that's eleven switch flips to accomplish the task. I forgot that was part of the question.
  Posted by Charlie on 2003-11-02 20:29:10

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