Problem 44756. Lights Out 5 - 5x5, 10 moves

Created by goc3

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Lights Out is a logic game wherein all lights need to be turned off to complete each board. See the first problem in the series for an introduction.

This problem contains boards that each require ten moves to solve. For example, if

 board = [0 1 1 0 1  
          1 1 1 1 1  
          1 1 1 1 1  
          1 1 1 1 1  
          0 1 1 0 1]

an answer is:

 moves = [1 2 3 4 5 16 17 18 19 20]

Prev.: 5x5, 8 moves — Next: 5x5, 13 moves

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30 Solutions
16 Solvers

Last Solution submitted on Apr 30, 2025

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8 Comments

8 Comments

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William on 12 Nov 2018

There seems to be a problem with Lights Out 5. Test cases 4 and 11 can be solved in fewer than 10 moves. Case 4 is solved by [1 3 5 21 23 25], which is easily verified by hand. Case 11 takes 9 moves -- [1 3 7 12 15 16 22 24 25].

li haitao on 13 Nov 2018

@goc
1 William is right.
2 Next problem of this series could be "Lights Out - 5x5, from 3 to 10 moves", I think it is more difficult than this one.

li haitao on 13 Nov 2018

@goc3 Sorry for misspell your name, but I can not delete the comment because of bug of cody.

goc3 on 13 Nov 2018

@William: thanks for catching that. Actually, test case 4 was intentional, as it can also be solved in 10 moves. But, to prevent future confusion, I have replaced it. And, test case 11 was indeed an error—it has been fixed.

goc3 on 13 Nov 2018

@li haitao: the test suite has been updated. Also, problem #7 in the series (not out yet, but will be soon) is similar to what you suggest. Thanks for the comments.

li haitao on 14 Nov 2018

@goc3
A piece of advice, measure the running time(using tic, toc, for example) in the test suit to see which solution is fast.

goc3 on 15 Nov 2018

@li haitao: I got 3.838179s (total time for test suite) for William's solution and 0.986936s (1/4 the time) for your sped-up version. Impressive.

Augusto Mazzei on 3 Oct 2019

i am surprised about the fact that some test admit a shorter solution than 10 moves :S

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Problem 44756. Lights Out 5 - 5x5, 10 moves

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Problem 44756. Lights Out 5 - 5x5, 10 moves

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Last 200 Solutions

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Problem Recent Solvers16

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