Island - a very elegant logic puzzle

For fans of all other kinds of logic puzzles

Re: Island - a very elegant logic puzzle

Postby Para » Sat Apr 07, 2012 9:51 am

dyitto wrote:It was speeded up by checking if two landcells can be found that are definitely separated by a water line - which was actually quite easy to program.
The second puzzle was solved in 3 hrs. Checking that the solution is unique was at least ready when I looked the next morning.


I'm not very surprised that one takes long because it employs a few observations at the start that i assume are hard to program. As they are all the same number and not connectable with one area of 8 cells, every clue needs at least 2 sections. Then the second observation is that because all numbers are seperated by at least 2 cells, except for one pair so all size 7 islands would have to touch one of those cells.
Those were the 2 ideas I set at the start after placing the first 2 clues in the top left corner. As long as I would make sure all 8s were spread enough and were never 1 or fewer cells apart, I would be sure the logic I used i the beginning would hold.
Para
 
Posts: 46
Joined: 20 February 2007

Re: Island - a very elegant logic puzzle

Postby dyitto » Sat Apr 07, 2012 11:39 am

Another one:
Code: Select all
3;.;.;.;7;.;.;.;.
.;3;.;.;.;.;.;.;4
.;4;.;.;.;2;.;1;.
.;.;.;2;.;.;.;.;.
.;.;7;.;.;4;.;.;.
.;.;.;.;5;.;.;1;.
.;.;.;.;.;.;3;.;.
.;2;.;.;.;.;.;3;.
2;.;4;.;3;2;.;.;.

I'll put my program online as soon as the UI is a bit more decent.
evert on the crashed forum
User avatar
dyitto
 
Posts: 118
Joined: 22 May 2010
Location: Amsterdam

Re: Island - a very elegant logic puzzle

Postby dyitto » Sat Apr 07, 2012 9:30 pm

simon_blow_snow wrote:I should also try to write a short program to verify uniqueness using brute force. Should not be too hard I suppose?

You can check my solver here:
http://www.scrybqj.com/downloads/island/
Last edited by dyitto on Sat Aug 11, 2012 11:33 pm, edited 1 time in total.
evert on the crashed forum
User avatar
dyitto
 
Posts: 118
Joined: 22 May 2010
Location: Amsterdam

Re: Island - a very elegant logic puzzle

Postby dyitto » Sun Apr 08, 2012 7:58 am

Another puzzle:
Code: Select all
.;.;.;.;.;2;.;.;.
7;.;.;.;7;.;.;.;.
.;.;.;.;.;.;5;.;.
.;.;.;5;.;.;.;.;.
.;6;.;.;.;3;.;.;5
.;.;.;.;.;.;.;.;.
.;.;.;.;8;.;.;.;.
.;2;.;3;.;7;.;.;.
.;2;.;.;.;.;.;4;.
evert on the crashed forum
User avatar
dyitto
 
Posts: 118
Joined: 22 May 2010
Location: Amsterdam

Re: Island - a very elegant logic puzzle

Postby simon_blow_snow » Sun Apr 08, 2012 1:26 pm

dyitto wrote:Another puzzle:
Code: Select all
3;.;.;.;7;.;.;.;.
.;3;.;.;.;.;.;.;4
.;4;.;.;.;2;.;1;.
.;.;.;2;.;.;.;.;.
.;.;7;.;.;4;.;.;.
.;.;.;.;5;.;.;1;.
.;.;.;.;.;.;3;.;.
.;2;.;.;.;.;.;3;.
2;.;4;.;3;2;.;.;.


It is a very nice medium-level puzzle! 8-)

Solution: Show
Code: Select all
3@@@7@@@@
#3######4
@4#@#2@1#
@#@2#@###
@@7#@4###
##@@5@#1#
#####@3@#
@2#@@##3#
2@4@32@@#

dyitto, when you run your solver program on the other five of Para's puzzles as well as stages 3 & 4 of Naoki's, don't forget to tell us how they go. ;-)
Last edited by simon_blow_snow on Mon Apr 09, 2012 10:46 am, edited 1 time in total.
User avatar
simon_blow_snow
 
Posts: 85
Joined: 26 December 2010

Re: Island - a very elegant logic puzzle

Postby dyitto » Mon Apr 09, 2012 7:12 am

Did you solve both of my 9x9 puzzles? If one starts with random numbers they probably tend to be medium-level.

As for the other puzzles, my program usually confirms unique solution, and run-times differ from few seconds to 20 minutes to few hours.
evert on the crashed forum
User avatar
dyitto
 
Posts: 118
Joined: 22 May 2010
Location: Amsterdam

Re: Island - a very elegant logic puzzle

Postby simon_blow_snow » Mon Apr 09, 2012 10:44 am

dyitto wrote:Did you solve both of my 9x9 puzzles? If one starts with random numbers they probably tend to be medium-level.

As for the other puzzles, my program usually confirms unique solution, and run-times differ from few seconds to 20 minutes to few hours.

Oopsy, I totally did not realise you posting a 3rd puzzle (even though I quoted your 3rd puzzle instead of the 2nd puzzle above). I just solved your 1st & 2nd ones.

You can make it clearer by including a title on top of your puzzle text (e.g. dyitto #1, dyitto #2).

Will have a go at your 3rd puzzle later.
User avatar
simon_blow_snow
 
Posts: 85
Joined: 26 December 2010

Previous

Return to Other logic puzzles

cron