The New Sudoku Players' Forum

[Quitschi]

Hey all of out there.


I tried this Sudoku from Su-Doku Time and got stuck. (Original grid on the left, the point I got to on the right)
An online solver I found (http://www.sudoku-lobby.de/sudoku-loesung/sudoku.sudoku?IDraster=482745) suggests to fill in a 7 in the first row fourth cell by the logic of trial and error - I don't like that.
So is there some logic solving method I am missing or is it only possible to go on by trial and error?

Sudoku 26.9.13.jpg (74.87 KiB) Viewed 1253 times

Thanks in advance for any comments and many greetings.

Q

[JasonLion]

You can continue from there using locked candidates, and naked pairs/triples. There is no need for either guessing or trial and error.

[ArkieTech]

Code: Select all

 *-----------*
 |...|...|..6|
 |..2|.8.|.3.|
 |..9|6.4|...|
 |---+---+---|
 |...|.5.|68.|
 |..5|.71|2..|
 |14.|...|..7|
 |---+---+---|
 |3..|..7|...|
 |71.|..8|...|
 |9..|...|.5.|
 *-----------*
 *-----------------------------------------------------------*
 | 458   378   1     | 237   23    59    | 489   27    6     |
 | 456   67    2     | 17    8     59    | 149   3     459   |
 | 58    378   9     | 6     123   4     | 18    127   258   |
 |-------------------+-------------------+-------------------|
 | 2     9     7     | 4     5     3     | 6     8     1     |
 | 68    68    5     | 9     7     1     | 2     4     3     |
 | 1     4     3     | 8     6     2     | 5     9     7     |
 |-------------------+-------------------+-------------------|
 | 3     5     468   | 12    1249  7     | 1489  126   2489  |
 | 7     1     46    | 5     249   8     | 3     26    249   |
 | 9     2     48    | 13    134   6     | 7     5     48    |
 *-----------------------------------------------------------*
In row 9 there is a pair of 48 (all other cells in r9 cannot contain a 4 or 8
r9c5 can drop the 4 making it a 13
This makes a 13 pair in block 8 (middle bottom).
The 1 can be removed from r7c4 allowing it to be set as a 2

Now can you find a triple in row 1?

[Pat]

Code: Select all

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


it's a 2-move puzzle

b2 "naked" duo --> r1 trio