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Lights switched (Posted on 2009-06-03) Difficulty: 4 of 5
Consider a 3x3 array of lighted buttons:
[O][O][O]
[O][O][O]
[O][O][O]
If any one of these buttons is pressed, it and all of its directly adjacent neighbors will toggle their status on/off. (Diagonals do not change.)

The goal is to get all of the lights to be off. Which buttons must be pressed to accomplish this?

Which buttons would accomplish this goal in the minimum number of presses for 4x4, 5x5, 6x6, 7x7, 8x8, and 9x9 arrays?

A nice site with the game from 3 x 3 up to 8 x 8 is here.

No Solution Yet Submitted by Jer    
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re(3): computer solution | Comment 4 of 5 |
(In reply to re(2): computer solution by Charlie)

Thank you for your quick reply.

What I meant was if you found, say 10100 you wouldnt have to list (or even try 00101).

No matter your program seems fast enough.  And they are easy enough to remove by inspection.

Now to search for patterns...

  Posted by Jer on 2009-06-04 13:48:23

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