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 Lights Out! (Posted on 2003-11-02)
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)

 Subject Author Date Puzzle Thoughts K Sengupta 2022-05-19 00:12:08 re: well one way Gamer 2003-11-07 07:10:13 re: Lights On! Charlie 2003-11-06 17:29:55 Lights On! wonshot 2003-11-06 12:24:16 well one way Joe C 2003-11-06 07:54:52 re(3): Brute Force Charlie 2003-11-04 00:39:10 re(2): Brute Force Charlie 2003-11-03 23:18:07 re: Brute Force Tristan 2003-11-03 18:58:17 Oh hell nevermind. Choop 2003-11-03 01:17:29 ANSWER HERE. Choop 2003-11-03 01:12:10 real-world method Lee 2003-11-02 23:32:30 No Subject Lee 2003-11-02 23:28:45 re: Brute Force Charlie 2003-11-02 20:29:10 re(2): Brute Force Charlie 2003-11-02 20:19:59 re: Brute Force rerun141 2003-11-02 19:49:19 Brute Force Charlie 2003-11-02 18:01:31 re(3): First steps to proof Victor Zapana 2003-11-02 17:16:50 re(2): First steps to proof rerun141 2003-11-02 16:36:36 re: First steps to proof Victor Zapana 2003-11-02 16:16:31 First steps to proof Tristan 2003-11-02 15:56:24 possibly impossible Victor Zapana 2003-11-02 14:05:48 re: Solution or impossible Victor Zapana 2003-11-02 13:42:26 Solution or impossible Gamer 2003-11-02 11:00:45 re: stuck lol rerun141 2003-11-02 10:48:03 stuck lol Victor Zapana 2003-11-02 09:14:54 re: question to gamer Victor Zapana 2003-11-02 09:00:38 question to gamer Victor Zapana 2003-11-02 08:57:31

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