The New Sudoku Players' Forum

[littlebabynothing]

Hi, i'm stuck on this puzzle which is a "hard" from the Papacom software. I've been trying for ages and just can't get any further than this! I noticed when I bought the software that you seem to really know what your doing, I think it might need one of your fancy multiple row x-boxes or something which I never really understood. I would really appreciate any ideas. Sorry about the messy grids it was the best I could manage and even these took me ages, I hope you can read them.

Original puzzle:

Code: Select all

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


My try so far:

Code: Select all

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


with pencil marks:

Code: Select all

25      25           8    |  6      9     3    |  4    7        1
9        67           367|  2      1     4    |  8    36       5
36      4             1    |  7      8     5    | 9    36       2
-----------------------------------------------------------
567     1567       9    |  45     3    167  | 2   8        47
25678  125678   567 |  459   67  1678| 57  1459   3
578     3            4     |  59    2    178  | 6    159    79
-------------------------------------------------------------
35678  5678     3567 |  1     4     2     | 57   59    679
4         9          567   |  3     567  67   | 1     2      8
1         567       2      |  8     567  9     | 3    45     674


[tarek]

hi ittlebabynothing,

according to your pencilmarks, the next step would be:

Code: Select all

*--------------------------------------------------------------------------*
| 25      25      8      | 6       9       3      | 4       7       1      |
| 9       67      367    | 2       1       4      | 8       36      5      |
| 36      4       1      | 7       8       5      | 9       36      2      |
|------------------------+------------------------+------------------------|
| 567     1567    9      | 45      3       167    | 2       8       47     |
| 25678   125678  567    | 459     67      1678   | 57      1459    3      |
| 578     3       4      | 59      2       178    | 6       159     79     |
|------------------------+------------------------+------------------------|
| 35678   5678    3567   | 1       4       2      | 57      59      679    |
| 4       9       567    | 3       567     67     | 1       2       8      |
| 1       567     2      | 8       567     9      | 3       45      467    |
*--------------------------------------------------------------------------*
r5c4 Must only have 49 as valid Candidates (49 is a Hidden Double in Row 5)
r5c8 Must only have 49 as valid Candidates (49 is a Hidden Double in Row 5)

Tarek

[vidarino]

You appear to have a naked triple (567, 67 and 57) in row 5, which means that none of these values can appear outside of the triple, and you can eliminate them from the rest of the row.

Doing that will reveal another naked triple in the same row, which will in turn unlock a few singles.

Good luck and happy puzzling.

Vidar

[Animator]

About the grids: Did you prepare them in Microsoft Word (or in another Text Editor)? If you did: make sure to select a fixed font. (Courier New for example)

The key to solving it is row 5:

It has a hidden pair: 4, 9
A naked triple: 5, 6, 7
A hidden triple: 1, 2, 8

(The only one you really need to make another move is the hidden 4, 9 pair. It allows you to fill in something in column 8)

[littlebabynothing]

That's brilliant! Thanks ever so much for your quick replies, I knew you'd have a solution!

[Crazy Girl]

For more basic skills try looking at the following sites

http://www.angusj.com/sudoku/hints.php
http://www.simes.clara.co.uk/programs/sudokutechniques.htm