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5*5 difficult on 24th May 2016
http://www.calcudoku.org/forum/viewtopic.php?f=18&t=795
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Author:  randomfruit  [ Tue May 24, 2016 8:21 pm ]
Post subject:  5*5 difficult on 24th May 2016

I think there's an error in this puzzle (http://www.calcudoku.org/en/2016-05-24/5/3).

I think the box c3*d3*c4*d4=60 could be a mistype for c3*d3*c4*d4=180, or,
d5~e5=3 could be a mistype for d5~e5=1. (Writing a~b to mean abs(a-b).)

Taking either, but not both, of these results in a soluble puzzle.

Of these two, the error d5~e5=1 seems the better, as it results in one solution, whereas
c3*d3*c4*d4=1 results in two feasible solutions:

53142
41523
24351
12435
35214

and

43152
51423
24531
12345
35214

Author:  pnm  [ Tue May 24, 2016 9:06 pm ]
Post subject:  Re: 5*5 difficult on 24th May 2016

randomfruit wrote:
I think there's an error in this puzzle (http://www.calcudoku.org/en/2016-05-24/5/3).

Both solutions you give are not solutions to the puzzle on the page though (?)

Edit: for reference, here is the puzzle:

Image

Author:  randomfruit  [ Wed May 25, 2016 9:24 pm ]
Post subject:  Re: 5*5 difficult on 24th May 2016

OK, now I've seen the solution, and I see that my solver had a bug. It did NOT produce any correct solution to the puzzle, but it did show some 'wrong' solutions when I removed a condition, leading to my comments before.

The solver is basically SQL:

select a1,a2, etc, b1, b2, etc, #there are 25 tables with names a1 thru e5,
from a1,a2, etc, b1, b2, etc, # each of which has one column with the same name as the table
where a1!=b1 and etc # and each of which contains the numbers 1..5
and a1!=a2 and etc # There are not-equal conditions to prevent duplicates
and a1+b1+a2=12 # and then the puzzle statement...
and (c1-d1-c2=0 or d1-c1-c2=0 or c2-c1-d1=0)
and e1*d2*e2=12
and b2*a3*b3=8
and c3*d3*c4*d4=60
and (e3/e4=5 or e4/e3=5)
and (a4-b4-a5=0 or b4-a4-a5=0 or a5-a4-b4=0)
and b5+c5=7
and abs(d5-e5)=3;

I was running this thru MySQL Workbench and their InnoDB engine.

I got outputs as described when I 'removed' a condition, i.e., commented-out
# and c3*d3*c4*d4=60

So my SQL code for the problem was wrong, and I found one mis-coded variable name in a condition like "and a1!=a2".
It was relatively easy to find using the enhanced windows editor "notepad++" (obtainable from fosshub.org) which put highlights into a source text showing every use of a variable when you double-click on it once.

My MySQL solver now finds a correct solution.

Author:  pnm  [ Thu May 26, 2016 8:55 am ]
Post subject:  Re: 5*5 difficult on 24th May 2016

randomfruit wrote:
OK, now I've seen the solution, and I see that my solver had a bug. It did NOT produce any correct solution to the puzzle, but it did show some 'wrong' solutions when I removed a condition, leading to my comments before.

Ah... so that's how you get all those points! [lol]

How long does it run on larger puzzles, say a 9x9?

Patrick

Author:  marblevolcano  [ Mon Jul 25, 2016 3:07 pm ]
Post subject:  Re: 5*5 difficult on 24th May 2016

randomfruit wrote:
I think there's an error in this puzzle (http://www.calcudoku.org/en/2016-05-24/5/3).

I think the box c3*d3*c4*d4=60 could be a mistype for c3*d3*c4*d4=180, or,
d5~e5=3 could be a mistype for d5~e5=1. (Writing a~b to mean abs(a-b).)

Uhhh... what?

This link takes me to a puzzle with negative numbers (2 through -2). It still says the same date, just not the same puzzle. [confused]
And also, I still scored 3 points for it even though it was two months ago. [mellow]

Author:  marblevolcano  [ Mon Jul 25, 2016 3:17 pm ]
Post subject:  Re: 5*5 difficult on 24th May 2016

marblevolcano wrote:
And also, I still scored 3 points for it even though it was two months ago. [mellow]

My mistake! That was today's puzzle, for subscribers only (I think) but somehow I still got points [scared]
Well, at least I now know how to get 5x5 difficult subscriber only puzzles. Thanks randomfruit :-)

Author:  paulv66  [ Mon Jul 25, 2016 11:22 pm ]
Post subject:  Re: 5*5 difficult on 24th May 2016

marblevolcano wrote:
marblevolcano wrote:
And also, I still scored 3 points for it even though it was two months ago. [mellow]

My mistake! That was today's puzzle, for subscribers only (I think) but somehow I still got points [scared]
Well, at least I now know how to get 5x5 difficult subscriber only puzzles. Thanks randomfruit :-)


I also clicked on the link and it allowed me access to today's 5x5 difficult subscriber only puzzle. I earned an extra 3 points but I no longer have a star against my name indicating that I solved all today's puzzles.

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