The New Sudoku Players' Forum

[ramope26]

Hi All!

I've been trying for a while to solve this puzzle but without success. Can anyone help and also explain the solving technique used?

[RSW]

It's a BUG+1. Cell r8c5 can't be 1 or 4, because it would result in a non-unique solution. Therefore, r8c5 = 9. Then singles to the end.
http://sudopedia.enjoysudoku.com/Bivalu ... Grave.html

[ramope26]

Thanks RSW! And also thanks for the page, had just passed to advanced level puzzles and I'd never come across those techniques.

I've also been having a look at all the deadly pattern cases, and I guess I need to study them a bit more; I've got this, which I think is one of them, but I can't solve it either.

[SpAce]

Hi ramope26,

There are many ways to solve your second puzzle, but the most obvious ones are single-digit techniques with the digit 6. Pretty much everything is available: Skyscraper, 2-String Kite, Turbot Crane, Grouped Skyscraper (i.e. Finned X-Wing), Grouped Turbot Crane (i.e. Empty Rectangle)...

Here's the first one I happened to spot:

Code: Select all

.-----------------.-----------------.----------------.
| 3    *689  2    | 59   4     1    | *69   7    58  |
| 5     1    679  | 79   2     8    |  3    4    69  |
| 4     789  789  | 3    5679  5679 |  1    2    58  |
:-----------------+-----------------+----------------:
| 679   5    679  | 4    1     679  |  8    3    2   |
| 8     2    3    | 579  5679  5679 | #679  1    4   |
| 1    *679  4    | 2    8     3    | *679  5    9-6 |
:-----------------+-----------------+----------------:
| 2     789  1    | 6    79    4    |  5    89   3   |
| 679   4    5679 | 8    3     579  |  2    69   1   |
| 69    3    5689 | 1    59    2    |  4    689  7   |
'-----------------'-----------------'----------------'

Finned X-Wing: (6)c27\r16 fr5c7 => -6 r6c9; stte

The same as a chain:

Grouped Skyscraper: (6)r6c2 = r1c2 - r1c7 = (6)r56c7 => -6 r6c9; stte

PS. These kinds of questions should be posted at the Help with puzzles and solving techniques section.

[SpAce]

It's a BUG+1. Cell r8c5 can't be 1 or 4, because it would result in a non-unique solution.

It would actually result in no solution.