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Where do you get your puzzles?

 
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Fri Mar 31, 2006 5:45 pm    Post subject: Where do you get your puzzles? Reply with quote

I'm looking for a few recommended sites that offer good puzzles (I already use this site). It's not easy to define a "good" puzzle, but it would present a challenge, requiring more than the basic techniques, but not so tough that I couldn't solve them.

For example, I'd like someting that might be a tad easier than the "Daily Nightmare" but a little harder than this site's "Very Hard."
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Angel



Joined: 26 Mar 2006
Posts: 31

PostPosted: Sat Apr 01, 2006 7:50 am    Post subject: Reply with quote

I use www.sudoku-xls.com/puzzle.html

This is updated weekly (on Saturdays). The puzzles range in difficulty from easy to extra difficult. I only ever do the two hardest (difficult and extra difficult).

These may approach the level you're looking for.
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keith



Joined: 19 Sep 2005
Posts: 3136
Location: near Detroit, Michigan, USA

PostPosted: Sat Apr 01, 2006 4:20 pm    Post subject: Difficult puzzles Reply with quote

Marty,

Take a look at Paul's Pages:

http://www.paulspages.co.uk/sudoku/

Here is a nice puzzle from that site:

Code:


+----------------------+----------------------+----------------------+
| 8      357    13579  | 6      349    13     | 4579   47     2      |
| 69     4      23679  | 2389   5      38     | 6789   1      79     |
| 1569   256    12569  | 7      249    18     | 45689  468    3      |
+----------------------+----------------------+----------------------+
| 15     9      1358   | 2358   237    4      | 1237   237    6      |
| 2      356    13456  | 359    3679   3567   | 13479  347    8      |
| 7      368    3468   | 2389   1      368    | 2349   5      49     |
+----------------------+----------------------+----------------------+
| 3      25678  25678  | 145    467    9      | 124678 24678  147    |
| 56     1      2567   | 345    8      3567   | 23467  9      47     |
| 4      678    6789   | 13     367    2      | 13678  3678   5      |
+----------------------+----------------------+----------------------+




Best wishes,

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Apr 01, 2006 5:56 pm    Post subject: Reply with quote

Thanks, I'll look forward to sampling those sites.

Quote:
Here is a nice puzzle from that site:

Keith, as I was copying that down, I noticed that some 3s and 8s can be eliminated from box 2 and c6 because of the triple at the top of c6, but I don't yet know if that will open anything up.
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keith



Joined: 19 Sep 2005
Posts: 3136
Location: near Detroit, Michigan, USA

PostPosted: Sat Apr 01, 2006 6:24 pm    Post subject: Gone Fishing! Reply with quote

Marty,

After you make a few eliminations, you get to this position, where there is a Swordfish in the rows



and the complementary fish, also a Swordfish, in the columns



Note that each of these eliminates the same possibilities (the values <2> in the red highlighted cells).

After that, there are a number of XY-wings to be found, not all of which are needed to find the solution.

Best wishes,

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Apr 01, 2006 10:10 pm    Post subject: Reply with quote

Keith, as I mentioned, there were triples in box 2 in the original grid. There was also a single "9" in r9. After the eliminations therefrom, I did find a swordfish on the 2s. I don't know if I got to the same position you subsequently showed.

Although I found a couple of XY-Wing patterns, neither could eliminate anything. I then started a forcing chain based in r6c9. Right off the bat, the "4" yielded duplicate numbers, so I solved the cell with the "9" and went on to complete it.

I enjoyed the puzzle. It continues to fascinate me that, although these puzzles have uniques solutions, they certainly don't have unique solving methods. This is just the latest of many examples showing how different people arrive at the same answer by using different techniques.
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Sun Apr 02, 2006 5:19 pm    Post subject: Reply with quote

This sets me in mind of my (long gone) maths teaching days, when it felt good to let the class go with something that caught them, even if it was off syllabus. To return to Marty R's question . . .

. . . we've all got our own standards & desires. Mine are for sudokus that can be solved using 'logic alone,' which for me means no forcing chains / colour chains, etc., and especially not Nishio. And I like them to be easily printed out for pencil-and-paper soln. Here are my 2 other favourite sites, i.e. as well as this one:-

(1) Sudoku-san's hardest level (atrocious) routinely but not quite always includes X-Wing(s) which makes the puzzles about right for a lazy Irishman who doesn't want the hassle of working with candidate lists. 4 daily puzzles, archived for a fortnight, in a really well-presented website with a nice sense of humour. (Anyone who can publish a sudoku book that uses the letters S-H-I-T-E-D-O-K-U instead of digits has my vote.)

(2) Brainbasher (http://brainbashers.com/sudoku.asp) offers 6 puzzles daily, permanently archived. The 2 hardest levels include most of the 'logical' techniques (much better known to you than me I'm sure). Searching enough for most people.
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Mon Apr 03, 2006 1:22 am    Post subject: Reply with quote

Victor,

To say you've got your own standards and desires for solving Sudoku is one thing (which I totally agree with, not being a big fan of forcing chains myself) but when you say you like to do
Quote:
...sudokus that can be solved using 'logic alone,' which for me means no forcing chains / colour chains, etc., and especially not Nishio.

seems to imply that those techniques are not logical, which is just plain wrong, IMO. You've got every right to only use whatever techniques you want to solve puzzles, but that doesn't mean other techniques aren't just as valid.
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