Multiple Coloring??

Advanced methods and approaches for solving Sudoku puzzles

Postby yasmin » Tue Mar 07, 2006 1:50 pm

Hi Ron, it's frankly a relief to know I'm not the only one who thinks it's a tough one.... I'll try to post it in code soon. Tell me if you get any further. Yasmin
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Postby tarek » Tue Mar 07, 2006 6:00 pm

I tried the puzzle yasmin with my solver........

It is really a toughie, however I don't think that colouring will get u far on this one....

A total of 25 advanced moves needed (including 3 simple chains)..........

Heavy use of the Almost locked sets rules.....

This step was beautiful

Code: Select all
*--------------------------------------------------------------------------*
| 4567    467     1      | 4578    23458   234578 | 235     2358    9      |
| 45      8       35     | 145     9       12345  | 7       1235    6      |
| 2       79     *359    | 1578   *358     6      |*35      1358    4      |
|------------------------+------------------------+------------------------|
| 169     5       29     | 3       246     2479   | 8       247     127    |
| 68      236     4      | 5678    1       2578   | 9       235     237    |
| 189     123     7      | 4589    2458    24589  | 2345    6       123    |
|------------------------+------------------------+------------------------|
| 3       1479   ^89     | 2      -48      1489   | 6       47      5      |
| 145     124     6      | 1458    7       13458  | 234     9       238    |
| 4579    2479    2589   | 45689   34568   34589  | 1       2347    2378   |
*--------------------------------------------------------------------------*

which is just shy of that classic WXYZ wing

Tarek
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Postby emm » Wed Mar 08, 2006 9:25 am

I got these clues from these chains

r3c2=7 => r3c3=9 => r7c3=8 => r7c5=4
r3c2=9 => r3c5=8 => r7c5=4
and => r7c8=7

r4c8=2 => r9c8=4 => r6c7=4 => r4c5=6
r4c8=4 => r8c7=4 => 47/47 => r4c3=2 => r4c5=6
and => r9c4=6
and => r6c4=9

but am stuck here

Code: Select all
*--------------------------------------------------------------------*
 | 4567   467    1      | 4578   2358   23578  | 235    2358   9      |
 | 45     8      35     | 145    9      1235   | 7      1235   6      |
 | 2      79     359    | 1578   358    6      | 35     1358   4      |
 |----------------------+----------------------+----------------------|
 | 19     5      29     | 3      6      247    | 8      24     127    |
 | 68     236    4      | 578    1      2578   | 9      235    237    |
 | 18     123    7      | 9      258    2458   | 2345   6      123    |
 |----------------------+----------------------+----------------------|
 | 3      19     89     | 2      4      189    | 6      7      5      |
 | 145    124    6      | 158    7      1358   | 234    9      238    |
 | 4579   2479   2589   | 6      358    3589   | 1      234    238    |
 *--------------------------------------------------------------------*
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Postby aeb » Wed Mar 08, 2006 9:12 pm

em wrote:... am stuck here
Code: Select all
*--------------------------------------------------------------------*
 | 4567   467    1      | 4578   2358   23578  | 235    2358   9      |
 | 45     8      35     | 145    9      1235   | 7      1235   6      |
 | 2      79     359    | 1578   358    6      | 35     1358   4      |
 |----------------------+----------------------+----------------------|
 | 19     5      29     | 3      6      247    | 8      24     127    |
 | 68     236    4      | 578    1      2578   | 9      235    237    |
 | 18     123    7      | 9      258    2458   | 2345   6      123    |
 |----------------------+----------------------+----------------------|
 | 3      19     89     | 2      4      189    | 6      7      5      |
 | 145    124    6      | 158    7      1358   | 234    9      238    |
 | 4579   2479   2589   | 6      358    3589   | 1      234    238    |
 *--------------------------------------------------------------------*

Some easy fruit:
(8,7)2 > (1,7)!2 > ([12],8)2 > (4,8)4 > (6,7)!4 > (8,7)4 > (8,7)!2
X-wing on cols 5,7: (1,6)!2, (1,8)!2, (6,2)!2, (6,6)!2, (6,9)!2
etc
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Postby emm » Thu Mar 09, 2006 9:02 am

aeb – what do you mean by 'etc'? I’ve shaken the tree and the fruits have stopped falling. I’d love to see another move that doesn’t feel like brute force.

Code: Select all
 
 *-----------------------------------------------------------*
 | 457   6     1     | 4578  2358  3578  | 235   358   9     |
 | 45    8     35    | 145   9     1235  | 7     1235  6     |
 | 2     79    359   | 1578  358   6     | 35    1358  4     |
 |-------------------+-------------------+-------------------|
 | 19    5     29    | 3     6     247   | 8     24    17    |
 | 6     23    4     | 578   1     2578  | 9     235   237   |
 | 8     13    7     | 9     25    45    | 245   6     13    |
 |-------------------+-------------------+-------------------|
 | 3     19    8     | 2     4     19    | 6     7     5     |
 | 15    124   6     | 158   7     1358  | 34    9     238   |
 | 579   2479  259   | 6     358   3589  | 1     234   238   |
 *-----------------------------------------------------------*
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Postby aeb » Thu Mar 09, 2006 7:46 pm

em wrote:aeb – what do you mean by 'etc'? I’ve shaken the tree and the fruits have stopped falling. I’d love to see another move that doesn’t feel like brute force.

A very similar reply would be
(5,8)3 > ([456],9)127 > (5,9)2 > (5,2)3 > (5,8)!3
X-wing for digit 3 in rows 5,6, etc.
There are also bivalue forcing chains
(9,3)9 > (4,3)2 > (5,2)3 > (6,2)1 > (7,2)9 > (9,3)!9
(9,1)5 > (8,1)1 > (4,1)9 > (4,3)2 > (9,3)5 > (9,1)!5
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Postby yasmin » Thu Mar 09, 2006 9:33 pm

Hi, thanks for your replies, I still need to work through them to see that I can follow. In the meantime I'd like to know if the following is what you mean by "code" for this puzzle. I went from top left through the rows down to bottom right. Is this the way you do it?
By the way, the two 6's in r2c9 and r7c7 were my own solutions, they are not in the original puzzle.


Nr. 122 in book

..1…..9.8..9.7..2….6..4.5.3..8….4.1.9….7….6.3..2….5..6.7..9…….1..
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