deadlocked
MJOYPosted: Wed Dec 7 2016 05:14 pm

Not a tech probelm, but just wondering if people solved the June 28 2016 problem completely by logic or was it necessary to guess?  I keep trying over and over, and keep getting the same stuck board where I can't eliminate any more candidates. I notice some people solved it, so it must be possible, but I can't figure out where I'm going wrong.  Thanks for any feedback.


ZyntaxPosted: Wed Dec 7 2016 09:51 pm

I just solved it. Didn't solve it when it came out.

 

It's logic about 1/3 of the way through then I had to make a couple of guesses and go with it. Took me about 5 min to solve it.


The nice fishPosted: Thu Dec 8 2016 03:28 pm

I re-did it without having to guess, but there were some tricky moves. A lot of the squares came from being the only possible place were a necessary number could go. But the most difficult part was probably realizing that the square at 3 down, 7 left (the upper most one in the 10-column) could not be a 1, after that a lot more numbers fell out.


MJOYPosted: Fri Dec 9 2016 06:10 pm

Thanks to the two people who responded!

To the Nice Fish:  I used logic to get it to the point where there were so few "candidates" left that I could solve it in a few more seconds by guessing, but I'd still like to know how you did it purely with logic.I didn't have a 1 in the space you mentioned. I had 356 there.  I had 12 in the square beside it, and I just had to decide between the 1 and the 2 to solve the puzzle (it was 2); however, I had to try both out with the surrounding few squares, and I consider that "guessing". No matter how much I study the board, I can't see how to complete with pure logic, so I am really impressed that you did it.


The nice fishPosted: Sat Dec 10 2016 02:49 am

I'd love to tell you how I did it, but it's difficult without knowing exactly what the board looked liked when you got stuck and had to guess. Maybe you could post an image?


MJOYPosted: Sat Dec 10 2016 06:03 pm

Hi The Nice Fish,

I scanned it and tried to post the image but I couldn't figure out how to do it as a file. (It seemed to require a link, and I don't have a website right now that i could put it on.)  Now we're on a whole new support topic. How do you post an image that has been scanned as a file? Moderator?


The nice fishPosted: Sun Dec 11 2016 05:18 am

You could, for example, use imgur.com to upload the image, and then post the link. That would probably be easiest.


MJOYPosted: Sun Dec 11 2016 11:20 pm

Thanks for the suggestion! Here's the URL--see if it works.

http://imgur.com/a/GWV3l


The nice fishPosted: Tue Dec 13 2016 11:32 am

Your link works great :) Maybe I got lucky when I first solved it after your post, but I can't seem to be able to do it that easily again. I probably made a mistake that turned out to be correct.

Anyway, it is still possible to solve with logic, using the fact that the sum of these columns http://imgur.com/S4wa2pm.png are 29, while these rows http://imgur.com/JN3tkUt.png are 21. So the three squares not overlapping must have the sum 29-21=8, which is impossible using the 6. So that cell becomes a 3, and after that the rest falls out.

I do however realize that it is probably a lot faster to guess than finding this trick, but I think it's much more enjoyable being able to solve them without guessing :)


Last Edited: Tue Dec 13 2016 11:35 am
MJOYPosted: Wed Dec 14 2016 11:55 am

Thank you so much for taking the time to share this with me. I loved your "logic" solution--I would never have thought of that strategy myself, and it was good for my elderly brain to study it until I understood it. I will try it out next time I have another deadlock on a hard practice puzzle and don't want to guess..  Also, thanks for telling me about Imgur--I once tried "Dropbox" but didn't like it; I  found Imgur easier to deal with, and it will come in handy.


The nice fishPosted: Wed Dec 14 2016 12:22 pm

Glad I could help :)