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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: ( You must be logged in to post comments.)
  Subject Author Date
Some ThoughtsPuzzle ThoughtsK Sengupta2022-05-19 00:12:08
re: well one wayGamer2003-11-07 07:10:13
re: Lights On!Charlie2003-11-06 17:29:55
Lights On!wonshot2003-11-06 12:24:16
Solutionwell one wayJoe C2003-11-06 07:54:52
re(3): Brute ForceCharlie2003-11-04 00:39:10
re(2): Brute ForceCharlie2003-11-03 23:18:07
re: Brute ForceTristan2003-11-03 18:58:17
Oh hell nevermind.Choop2003-11-03 01:17:29
ANSWER HERE.Choop2003-11-03 01:12:10
Hints/Tipsreal-world methodLee2003-11-02 23:32:30
No SubjectLee2003-11-02 23:28:45
Solutionre: Brute ForceCharlie2003-11-02 20:29:10
re(2): Brute ForceCharlie2003-11-02 20:19:59
re: Brute Forcererun1412003-11-02 19:49:19
SolutionBrute ForceCharlie2003-11-02 18:01:31
re(3): First steps to proofVictor Zapana2003-11-02 17:16:50
Questionre(2): First steps to proofrerun1412003-11-02 16:36:36
Some Thoughtsre: First steps to proofVictor Zapana2003-11-02 16:16:31
Some ThoughtsFirst steps to proofTristan2003-11-02 15:56:24
possibly impossibleVictor Zapana2003-11-02 14:05:48
re: Solution or impossibleVictor Zapana2003-11-02 13:42:26
Solution or impossibleGamer2003-11-02 11:00:45
re: stuck lolrerun1412003-11-02 10:48:03
stuck lolVictor Zapana2003-11-02 09:14:54
re: question to gamerVictor Zapana2003-11-02 09:00:38
question to gamerVictor Zapana2003-11-02 08:57:31
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