Help Solving Sudoku 2 (app) Expert Puzzle

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Help Solving Sudoku 2 (app) Expert Puzzle

Postby blueriley9 » Fri Aug 03, 2018 2:43 am

Hello!
I have found myself quite stuck on this puzzle and have sought techniques, restarted it etc...but can't find the next step.
Some advice would be fantastic!

Thank you very much for your time.

Without pencil marks

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


With my pencil marks

238 2389 289 I 4 28 6 I 1 7 5
12 4 5 I 7 12 9 I 6 8 3
6 7 18 I 18 3 5 I 2 49 49
----------------------+-------------------+-------------
248 1289 2489 I 168 168 128 I 5 3 7
5 28 6 I 3 4 7 I 89 1 29
2378 1238 278 I 9 5 128 I 48 6 24
-------------------------+-----------------+---------------
278 258 3 I 158 178 18 I 49 49 6
14 56 14 I 56 9 3 I 7 2 8
9 68 78 I 2 678 4 I 3 5 1

I have a photo of it as well if there's an easy way to attach/link that
blueriley9
 
Posts: 2
Joined: 03 August 2018

Re: Help Solving Sudoku 2 (app) Expert Puzzle

Postby speter » Fri Aug 03, 2018 11:05 am

I think this is a very challenging puzzle, especially if you are solving it by hand.

There is a hidden triple (candidates 1,3,9) at r1c2, r4c2 & r6c4; which means you can remove candidates 2 & 8 @ r1c2, r4c2 & r6c4.
The move after that is a X-Wing; and then an AIC.

Good Luck.
speter
 
Posts: 16
Joined: 30 March 2017

Re: Help Solving Sudoku 2 (app) Expert Puzzle

Postby SpAce » Fri Aug 03, 2018 11:42 am

speter wrote:There is a hidden triple (candidates 1,3,9) at r1c2, r4c2 & r6c4; which means you can remove candidates 2 & 8 @ r1c2, r4c2 & r6c4.

A little typo: the third member of the hidden triple is r6c2 (not r6c4). Also, I'd say the corresponding naked quad (2568)r5789c2 is probably easier to find when pencil marks are used (and produces the same eliminations).

The move after that is a X-Wing; and then an AIC.

I guess you meant XYZ-Wing instead of X-Wing? Anyway, there's also a relatively simple one-step solution after the mentioned hidden triple/naked quad:

Code: Select all
.------------------.---------------.------------.
| 238   39   89-2  | 4    28   6   | 1   7   5  |
|*1(2)  4    5     | 7    12   9   | 6   8   3  |
| 6     7   *18    | 18   3    5   | 2   49  49 |
:------------------+---------------+------------:
| 48-2  19   2489  | 168  168  128 | 5   3   7  |
| 5     28   6     | 3    4    7   | 89  1   29 |
| 378-2 13  *(2)78 | 9    5    128 | 48  6   24 |
:------------------+---------------+------------:
| 278   258  3     | 158  178  18  | 49  49  6  |
| 14    56   14    | 56   9    3   | 7   2   8  |
| 9     68  *78    | 2    678  4   | 3   5   1  |
'------------------'---------------'------------'



WXYZ-Wing: (2=1)r2c1 - (1=872)r369c3 => -2 r1c3,r46c1; lclste

In other words, at least one of the 2s (r2c1 or r6c3) must be true, which makes the three other 2s (r1c3, r4c1, r6c1) that see both of them false. After that basic solving will suffice.
Code: Select all
   *             |    |               |    |    *
        *        |=()=|    /  _  \    |=()=|               *
            *    |    |   |-=( )=-|   |    |      *
     *                     \  ¯  /                   *   
SpAce
 
Posts: 681
Joined: 22 May 2017

Re: Help Solving Sudoku 2 (app) Expert Puzzle

Postby blueriley9 » Fri Aug 03, 2018 8:05 pm

wow, thank you very much!
blueriley9
 
Posts: 2
Joined: 03 August 2018


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