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zaks
Joined: 25 Nov 2005 Posts: 13

Posted: Wed Dec 14, 2005 5:28 pm Post subject: 14 Dec 2005 very hard sudoku: solution 


14 Dec 2005 v.h. sudoku: solution
("!" means "good/hard move" )
("!!" means "very good/hard move" )
6b5 2i7
3f5! ( see column f )
3g6
1e6! ( due to 1 in cell a4, in box 6 the 1 should be in cells h5 or i5,
in turn that means that in box 5 the 1 can be only in e6! )
2g4
4d5! ( see col d )
4c3
6d2! (see col d )
now we need excluding some candidates:
6e9! 7e8! 7e7! 9h9! 9h8!
this allows to make move
9g8 (see col d )
and again we exclude candidates:
9a5! (in row 6, the 9 must be in one of cells a6,b6,c6,
that means that
in box 4, the 9 must be excluded as candidate from a5 )
and now the most good/hard move:
1c9!! ( see cells f8,h8,i8:
candidates in f8 are 7,8; in h8 & i8 candidates are 1,7,8;
this means that
in box 3, the 1 should be in h8 or g8, not in g9 or i9,
and then in row 9 we have the only cell for 1  c9!!)
the rest moves are more/less easy to follow:
1b3 8g3 2d3 8d6 6f4 9e4 2e5 6g9 1g1 8a5 1i5 9h5
8e2 5e9 4e8 6e7 3a9 5b8 8i9 7i8 1h8 3h7 8f8 7f7
5i4 8h4 3i3 6i1 7e3 5h3 7h2 3e1 3c2 2b2 5a2 4a3
9a7 4b7 8c7 9b6 7c6 2a6 7a1 9c1 x!
enjoy, zaks
ps of course ! & !! are highly subjective evaluations of moves... 

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Guest Guest

Posted: Thu Dec 15, 2005 6:51 pm Post subject: Please Help me understand your notations 


Hi  I'm new to this. This puzzle has me stumped.
Are you calling the columns a  i and the rows 19?
If so  I understand 6b5 to mean a 6 in column b row 6. Is that right?
If it is, then I do not get 2i7. There's already a 2 in that 3x3 box/square.
Thanks for giving me a hand in following your notation. T 

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David Bryant
Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Posted: Thu Dec 15, 2005 7:39 pm Post subject: Re: Please Help me understand your notations 


Guest wrote:  Hi  I'm new to this. This puzzle has me stumped.
Are you calling the columns a  i and the rows 19? 
Yes, sort of. "Zaks" used to number the rows from 1 to 9 (top to bottom), and the columns from a  i (left to right). But starting on December 13 he got mixed up, and started numbering the rows from the bottom to the top.
Guest wrote:  If so  I understand 6b5 to mean a 6 in column b row 6. Is that right? 
I think you made a typo. "6b5" means "place a 6 in row 5, column 2." Notice that row 5 is the same row no matter which way you number the rows.
Guest wrote:  If it is, then I do not get 2i7. There's already a 2 in that 3x3 box/square. 
Well, you're misinterpreting what "Zaks" said, because he's numbering his rows upside down today. So "2i7" means "place a 2 in row 3, column 9," which is clearly right, looking at the initial grid.
Guest wrote:  Thanks for giving me a hand in following your notation. T 
I think it would help if "Zaks" would number the rows and columns consistently. dcb 

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Guest Guest

Posted: Thu Dec 15, 2005 7:40 pm Post subject: I got it! 


OK  using hidden pairs, I was finally able to solve this puzzle. I was stumped before using that technique. Once I tried that, it didn't seem so hard at all!
Still curious about the notation above, though. T 

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Guest  T Guest

Posted: Thu Dec 15, 2005 7:43 pm Post subject: Thanks, David 


Maybe Zaks is left handed? Your explanation makes sense. T 

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Guest

Posted: Thu Dec 15, 2005 7:52 pm Post subject: Re: 14 Dec 2005 very hard sudoku: solution 


dear zaks , as a beginner could you give the answers as if you were trying to show a 12 yr old. i do not have the slightest idea what you are talking about. 

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David Bryant
Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Posted: Thu Dec 15, 2005 8:31 pm Post subject: Using the "draw" program 


Guest wrote:  OK  using hidden pairs, I was finally able to solve this puzzle. I was stumped before using that technique. Once I tried that, it didn't seem so hard at all! 
Good for you!
Here are a couple of suggestions. If you do get stuck on one of Samgj's puzzles, you can always put the puzzle into the draw program to get a pretty good hint. Then, if the logic behind the hint is not apparent, you may want to post your position in the forum and ask for suggestions  there are a lot of good people here who can explain the hints for you. dcb 

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