dailysudoku.com

ravel · Joined: 21 Apr 2006 Posts: 536

This is the puzzle, i posted in the "Daily Sudoku puzzles" forum here.

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

.....I'll add the comments I made on the last thread. I had to find 5 pairs and a triple before I entered my first number. Then a couple of xy wings and a UR. Then a lot more pairs and a triple. Then I got stuck.

ravel · Joined: 21 Apr 2006 Posts: 536

Hm, dont know now, where you are.
Beside of some pairs and locked candidates (note the hidden pair 45 in column 2, both locked to the same cells) there is an xy-wing needed for the first number. Then a couple of locked candidates, pairs and triples should bring you here.

Earl · Joined: 30 May 2007 Posts: 677 Location: Victoria, KS

Two swordfish opened the puzzle for me, a 1-2 punch.

Earl

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

.. well it's got me stumped and I got to exactly the same place. I'll keep looking.

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

.. alright I give up!! What am I missing??

Edited Later:

Oh Brother!! Forget the note above. I couldn't see the wood for the trees and missed the x-wing on 8's.

I'd say that was the most challenging sudoku I've encountered to-date. It has to be when there are 5 pairs and a triple to be found before starting.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

ok, so anyone else find it difficult to place any numbers after basics?? you needed the swordfish to solve the first cell.

edit: oops, nevermind, Ravel needed an xy-wing to get the first number.

keith · Posted: Tue Apr 08, 2008 8:34 pm Post subject:

Soapbox, again!

Right at the beginning, there is a pair <45> in R19C3. Look at the <45> in R5; There is a hidden pair <45> in B4.

Still a lot of work, but I think that after you find this hidden pair the candidates are much simplified.

I needed an X-wing, two XY-wings, and another X-wing. And, a zillion pairs.

Keith

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

Marty R. · Posted: Tue Apr 08, 2008 9:07 pm Post subject:

A fun puzzle, even though I had to do it three times. Three XY-Wings, two URs, coloring, and an M-Wing. The latter set up the third XY-Wing which finished it off.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

CORUJA · Posted: Wed Apr 09, 2008 8:13 pm Post subject: VH by gsf

Thanks Ravel, a very challenging puzzle! At least for me: had to do it two times. Very Happy

Coruja

keith · Posted: Wed Apr 09, 2008 10:04 pm Post subject:

Victor · Joined: 29 Sep 2005 Posts: 207 Location: NI

Whether you like doing 'basic moves' with candidate numbers or without is a matter of taste I guess. But I'm with Keith in suggesting that it's at least sometimes more efficient to do a fair bit without candidate numbers. (I happen to get a kick out of going as far as I can without candidate numbers, but I wouldn't in the least suggest that this is the 'best' method.)
E.g. you could here get a couple of pairs by observation: in columns 3 & 7 the top and bottom cells can't be 1/2/3/8: that just leaves pairs. In c3, the pairs are 45. Now if you slide your eyes up & down & across in box 4, you'll see another pair of 45s. And you'll also now see the X-wing in 5s: same 2 places in the top & bottom rows (so saves some pencil lead!). Nice puzzle.

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

... the bottom line for me is that this is still by far the best solvable/non-guessable sudoku I have encountered to-date. I would like to mention it again whenever we get another VH forum.
Hey - why not have a forum of the BEST SUDOKUS EVER.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

about the soapbox... the first puzzles I ever did were very easy and therefore I used pointing pairs and box/line interactions in my head, which I found were more efficient than actually writing in the candidates.

with the harder puzzles I would focus on certain cells to help remember which candidates belonged, etc.

its wasn't until I found out what naked pairs or hidden pairs were that I started writing in the pairs to make sure I did eliminate the right candidates.