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Old 2019-04-02, 15:14   #1
Xyzzy
 
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Default April 2019

http://www.research.ibm.com/haifa/po...April2019.html
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Old 2019-04-03, 13:45   #2
bsquared
 
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Easy to find solutions. I wonder what "elegant" looks like for this puzzle; mine surely are not.
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Old 2019-04-03, 14:35   #3
bsquared
 
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Found a solution for 4x4
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Old 2019-04-03, 14:50   #4
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Quote:
Originally Posted by bsquared View Post
Found a solution for 4x4
I stopped after 21x21. It seems pointless going further up.
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Old 2019-04-03, 14:59   #5
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Quote:
Originally Posted by a1call View Post
I stopped after 21x21. It seems pointless going further up.


Are all of your averages integers? I.e., all row/col/diag sums are 0 mod 21 as well as prime? If so then you have a much better search algorithm than me.
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Old 2019-04-03, 15:13   #6
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Quote:
Originally Posted by bsquared View Post


Are all of your averages integers? I.e., all row/col/diag sums are 0 mod 21 as well as prime? If so then you have a much better search algorithm than me.
Well shouldn't spoil the challenge at this point but there is a simple algorithm as a factor of number of rows as is obvious with the great number of solutions submitted this early.
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Old 2019-04-03, 16:46   #7
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Thanks for sharing. My year 10 class (aged 14-15) had great fun with this today.
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Old 2019-04-03, 17:55   #8
petrw1
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Default Yes quite easy indeed.

...
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Old 2019-04-07, 20:36   #9
a1call
 
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Well, I did a 101x101 matrix because I found it interesting to write a code to generate a code to solve the large matrix. Otherwise it would have been prohibitively too much work to type the code to check all the 101+101+2 averages.

ETA Again, I wished someone would write a "foreach" style function for the PARI-GP vectors/matrices or add a few decent numeric examples to the forvec loop documentation.

Last fiddled with by a1call on 2019-04-07 at 20:59
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Old 2019-04-08, 15:01   #10
LaurV
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Quote:
Originally Posted by bsquared View Post
all <...> sums are 0 mod 21 as well as prime?
now yafu is very angry with his daddy...
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Old 2019-04-09, 13:35   #11
bsquared
 
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Quote:
Originally Posted by LaurV View Post
now yafu is very angry with his daddy...
Not sure I get it...

Anyway, I picked this back up and figured out a few more things, but I don't think I'll bother to progress much beyond 6x6.
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