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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Tue Sep 18, 2007 1:12 pm    Post subject: Good Times Reply with quote

This is the puzzle used in the final of the Times sudoku championship, held on 16 September.

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

The winner, Tom Collier, completed it in 12 minutes 45 seconds.

I did not!

Steve
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Tue Sep 18, 2007 3:45 pm    Post subject: Reply with quote

Quote:
The winner, Tom Collier, completed it in 12 minutes 45 seconds.

I did not!


Did not what? Finish in 12 minutes 45 seconds? Finish? Wink
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Tue Sep 18, 2007 4:17 pm    Post subject: Reply with quote

It took me nearly an hour.

Steve
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Tue Sep 18, 2007 7:43 pm    Post subject: Reply with quote

Guessing that the puzzle in The Times sudoku final would use the same advanced steps like the Super Fiendish on Saturday,It could save me quite some time. and yes both steps where present in the grid.(the other one, more harder to detect, because IMO this advanced step is very rare used for solving the VH's in The Daily Sudoku.)

Nevertheless the fore knowledge of these two advanced steps, it took me twenty minutes more than Tom's time.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Sep 18, 2007 11:04 pm    Post subject: Reply with quote

I didn't time myself, but it took me about 30 minutes. I only needed one advanced step, which wasn't all that advanced. Basic methods (line-box and naked/hidden sets) got me here:
Code:
+------------------+------------------+------------------+
| 139   16    7    | 19    5     8    | 2     4     369  |
| 1249  146   129  | 19    3     7    | 8     5     69   |
| 8     5     39   | 6     4     2    | 1     39    7    |
+------------------+------------------+------------------+
| 5     29    6    | 24    1     49   | 3     7     8    |
| 7     3     89   | 58    6     59   | 4     1     2    |
| 12    18    4    | 28    7     3    | 9     6     5    |
+------------------+------------------+------------------+
| 6     29    239  | 7     8     1    | 5     239   4    |
| 123   7     1238 | 45    9     45   | 6     238   13   |
| 149   148   5    | 3     2     6    | 7     89    19   |
+------------------+------------------+------------------+

There is a 6-cell DP in R12C249. It includes an X-Wing on <6> (R12C29). So, <6> can be placed in R1C2 and R2C9 and the puzzle falls apart.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Sep 18, 2007 11:23 pm    Post subject: Reply with quote

Oops! Embarassed

I wrote too soon. I must have made a lucky error because my attempt to recreate the "puzzle falling apart" after the DP step didn't happen.

I had to use two more steps, one of them recently discussed on another thread involving coloring from a W-Wing (sort of "inverse multi-coloring). Here is the grid after the DP step:
Code:
+------------------+------------------+------------------+
| 139   6     7    | 19    5     8    | 2     4     39   |
| 1249  14    129  | 19    3     7    | 8     5     6    |
| 8     5     39   | 6     4     2    | 1     39    7    |
+------------------+------------------+------------------+
| 5     29r   6    | 24    1     49g  | 3     7     8    |
| 7     3    w89g  | 58    6     59r  | 4     1     2    |
| 12    18    4    | 28    7     3    | 9     6     5    |
+------------------+------------------+------------------+
| 6     29g   239  | 7     8     1    | 5    #23-9  4    |
| 123   7     1238 | 45    9     45   | 6     238   13   |
|#14-9  148   5    | 3     2     6    | 7    w89R   19   |
+------------------+------------------+------------------+

Note the {89} W-Wing that produces no direct elimination. However, the coloring shown eliminates <9> from the cells marked #.

After that, there is a {14} W-Wing in C12 that solves the puzzle.
[Edit for misspelling.]
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Wed Sep 19, 2007 7:39 pm    Post subject: Reply with quote

x-wing on 3 and then, here:
Code:

+--------------------------+--------------------------+--------------------------+
| 139     16      7        | 19      5       8        | 2       4       369      |
| 1249    146     129      | 19      3       7        | 8       5       69       |
| 8       5       39       | 6       4       2        | 1       39      7        |
+--------------------------+--------------------------+--------------------------+
| 5       29      6        | 24      1       49       | 3       7       8        |
| 7       3       89       | 58      6       59       | 4       1       2        |
| 12      18      4        | 28      7       3        | 9       6       5        |
+--------------------------+--------------------------+--------------------------+
| 6       29      239      | 7       8       1        | 5       239     4        |
| 123     7       128      | 45      9       45       | 6       28      13       |
| 149     148     5        | 3       2       6        | 7       89      19       |
+--------------------------+--------------------------+--------------------------+

xy-chain '29'(72)='92'(42)='21'(61)='18'(62)='89'(53)='93'(33)='39'(38 )='98'(98 )='82'(88 ) removes 2 from 3 cells: r7c8 r8c1 r8c3.
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Wed Sep 19, 2007 10:11 pm    Post subject: Reply with quote

The same x-wing on <3> and then a swordfish on <9>.

In R129C149 the swordfish eliminates <9> in R9C8 and in R2C3

Code:

+---------------+---------+-----------+
|*139  16  7    |*19 5 8  | 2 4  *369 |
|*1249 146 12-9 |*19 3 7  | 8 5  *69  |
| 8    5   39   | 6  4 2  | 1 39  7   |
+---------------+---------+-----------+
| 5    29  6    | 24 1 49 | 3 7   8   |
| 7    3   89   | 58 6 59 | 4 1   2   |
| 12   18  4    | 28 7 3  | 9 6   5   |
+---------------+---------+-----------+
| 6    29  239  | 7  8 1  | 5 239 4   |
| 123  7   1238 | 45 9 45 | 6 238 13  |
|*149  148 5    | 3  2 6  | 7 8-9 *19 |
+---------------+---------+-----------+
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