The New Sudoku Players' Forum

[DoubleB72]

Here is how it starts

*** *** *1*
5** *4* *2*
*98 **3 6**

*3* *5* 2*4
48* *** *71
7*6 *2* *9*

**9 6** 43*
*7* *8* ***
*4* *** ***

Here is as far as I can get

3 (2,6) 4 (2,5,7,8,9) (6,9) (2,6,7,8,9) (7,8,9) 1 (5,7,8,9)
5 (1,6) 7 (1,8,9) 4 (1,6,8,9) (3,8,9) 2 (3,8,9)
(1,2) 9 8 (1,2,5,7) (1,7) 3 6 4 (5,7,9)

9 3 1 (7,8) 5 (7,8) 2 6 4
4 8 2 (3,9) (3,6,9) (6,9) 5 7 1
7 5 6 (1,4) 2 (1,4) (3,8) 9 (3,8)

8 (1,2) 9 6 (1,7) 5 4 3 (2,7)
(1,2) 7 3 (1,2,4,9) 8 (1,2,4,9) (1,9) 5 6
6 4 5 (1,2,3,7,9) (3,9) (1,2,7,9) (1,7,9) 8 (2,7,9)

[TKiel]

Simple Sudoku says there are two solutions, so you may want to check that you posted the givens in the correct cells.

Tracy

[DoubleB72]

How does that help?

[DoubleB72]

I am sorry there is a 6 in rom 8 column 9

[TKiel]

DoubleB72,

If a puzzle has more than one solution it can't be solved by logical techniques alone, at some point you have to guess.

Use colouring on digit 1.

Tracy

[DoubleB72]

Colouring?

[Ruud]

Yep, colouring can do the trick.

on the other hand...

there is a sashimi swordfish that allows you to do a bit of damage:

Code: Select all

.------------------.------------------.------------------.
| 3     26    4    | 25789 69    26789| 789   1     5789 |
| 5     16    7    | 189   4     1689 | 389   2     389  |
|*12    9     8    | 1257 *17    3    | 6     4     57   |
:------------------+------------------+------------------:
| 9     3     1    | 78    5     78   | 2     6     4    |
| 4     8     2    | 39    369   69   | 5     7     1    |
| 7     5     6    | 14    2     14   | 38    9     38   |
:------------------+------------------+------------------:
| 8     12    9    | 6    #17    5    | 4     3     27   |
|*12    7     3    |-1249  8    -1249 |*19    5     6    |
| 6     4     5    |-12379 39   -1279 |*179   8     279  |
'------------------'------------------'------------------'

Please notice that there is almost a swordfish in the starred cells (3 columns with candidates in 3 rows). The swordfish is not complete. The # cell takes the place of one of the other cells that would make the swordfish complete.

Now either the #cell contains a 1, or the 'swordfish' would take effect. In both cases, the cells I marked with - can no longer contain candidate 1. The # cell is the only candidate left in that box.

Ruud.

[ronk]

This puzzle is also discussed here.

[Ruud]

Thanks Ron. I thought I recognized it, with the 4 eliminations.

That said, I'll never pass an opportunity to sell more fish.

Ruud.

[Cec]

Colouring?

Hi DoubleB72",
Click on HERE for an explanation of the "Colouring" technique. This link also explains some of the "basic" techniques for solving sudoku.
Cec