Help solving puzzle

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Help solving puzzle

Postby goldfish » Fri Feb 22, 2008 2:21 pm

Hello there,

I always thought that I was any good at solving Su Doku puzzles, but then I bought Wayne Gould's Extreme Su Doku and now I'm feeling a bit of an idiot!

Here's where I've got to on puzzle #2 on that book (I've given up on #1!)

Code: Select all
Puzzle:

. . . | 5 . 8 | . . .
. 1 . | 2 . 6 | . 8 .
3 . . | . 4 . | . . 2
------+-------+------
2 . 9 | . . . | 8 . 4
. . . | 4 . 2 | . . .
1 . 5 | . . . | 3 . 7
------+-------+------
6 . . | . 8 . | . . 1
. 5 . | 7 . 1 | . 4 .
. . . | 6 . 3 | . . .

Workings:

79    2679  2467  | 5     39    8     | 14679 13679 369
5     1     47    | 2     39    6     | 47    8     39
3     689   68    | 1     4     7     | 569   569   2
------------------+--------------------+-------------------
2     67    9     | 3     17    5     | 8     16    4
78    3678  3678  | 4     17    2     | 169   169   5
1     4     5     | 8     6     9     | 3     2     7
------------------+--------------------+-------------------
6     237   237   | 9     8     4     | 257   357   1
89    5     38    | 7     2     1     | 69    4     3689
4     2789  1     | 6     5     3     | 279   79    89



This is annoying the hell out of me because I'm sure I've checked all the doubleton's, x-wings, etc. But there's obviously something I've not checked yet, or got wrong with my workings... Any help much appreciated!
goldfish
 
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Joined: 22 February 2008

Postby ArkieTech » Fri Feb 22, 2008 2:33 pm

goldfish,

Code: Select all
 *--------------------------------------------------------------------*
 | 79     2679   2467   | 5      39     8      | 147-69 17-369 369    |
 | 5      1      47     | 2      39     6      | 47     8      39     |
 | 3      689    68     | 1      4      7      | 569    569    2      |
 |----------------------+----------------------+----------------------|
 | 2      67     9      | 3      17     5      | 8      16     4      |
 | 78     3678   3678   | 4      17     2      | 169    169    5      |
 | 1      4      5      | 8      6      9      | 3      2      7      |
 |----------------------+----------------------+----------------------|
 | 6      237    237    | 9      8      4      | 257    357    1      |
 | 89     5      38     | 7      2      1      | 69     4      3689   |
 | 4      2789   1      | 6      5      3      | 279    79     89     |
 *--------------------------------------------------------------------*

There is a 3569 quad in box 3 you can remove 369 from r1c78

dan
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Postby goldfish » Fri Feb 22, 2008 3:01 pm

ArkieTech wrote:
There is a 3569 quad in box 3 you can remove 369 from r1c78



Of course! Thank you!
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re: "Extreme Su Doku" -- puzzle 2

Postby Pat » Sun Mar 02, 2008 1:46 pm

ArkieTech wrote:
Code: Select all
 *--------------------------------------------------------------------*
 | 79     2679   2467   | 5      39     8      | 147-69 17-369 369    |
 | 5      1      47     | 2      39     6      | 47     8      39     |
 | 3      689    68     | 1      4      7      | 569    569    2      |
 |----------------------+----------------------+----------------------|
 | 2      67     9      | 3      17     5      | 8      16     4      |
 | 78     3678   3678   | 4      17     2      | 169    169    5      |
 | 1      4      5      | 8      6      9      | 3      2      7      |
 |----------------------+----------------------+----------------------|
 | 6      237    237    | 9      8      4      | 257    357    1      |
 | 89     5      38     | 7      2      1      | 69     4      3689   |
 | 4      2789   1      | 6      5      3      | 279    79     89     |
 *--------------------------------------------------------------------*


There is a 3569 quad in box 3 you can remove 369 from r1c78



yes there is a "naked" quartet ( in box 3 ) --
or you can avoid the "pencilmarks" and see the "hidden" trio {1,4,7} ( in that box )

Code: Select all
 . . . | 5 . 8 | . . .
 5 1 . | 2 . 6 | . 8 .
 3 . . | 1 4 7 | . . 2
-------+-------+------
 2 . 9 | 3 . 5 | 8 . 4
 . . . | 4 . 2 | . . 5
 1 4 5 | 8 6 9 | 3 2 7
-------+-------+------
 6 . . | 9 8 4 | . . 1
 . 5 . | 7 2 1 | . 4 .
 4 . 1 | 6 5 3 | . . .

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Unsolvable puzzle?

Postby gerrygeek » Tue Mar 04, 2008 9:42 pm

I believe I can solve ANY sudoku puzzle. Please post a one you believe to be insolvable and I will try to solve it.
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Re: Unsolvable puzzle?

Postby Cec » Wed Mar 05, 2008 1:40 am

gerrygeek wrote:I believe I can solve ANY sudoku puzzle. Please post a one you believe to be insolvable and I will try to solve it.
Gerrygeek

As this request doesn't seem to be related to this thread could I suggest it be made a new thread?

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Help solving puzzle

Postby Cec » Fri Mar 07, 2008 11:12 am

For further response to gerrygeek's request see Insoluable Sudoku Puzzles thread Here

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