X Sudoku (extreme)

For fans of Killer Sudoku, Samurai Sudoku and other variants

X Sudoku (extreme)

Postby morl » Sat May 19, 2018 6:44 pm

Code: Select all
...|63.|...
...|.5.|...
12.|4..|...
---+---+---
..3|...|8..
9..|...|..1
..5|...|4..
---+---+---
...|..7|.26
...|.9.|...
...|.84|...


Have fun!
morl
morl
 
Posts: 38
Joined: 12 February 2018

Re: X Sudoku (extreme)

Postby Leren » Sat May 19, 2018 8:44 pm

Too hard to solve in one move but I'll just illustrate a Sudoku X Move late in the solving process.

Code: Select all
*-----------------------------------------------------*
| 57    a5789   79    | 6   3  1   | 2     b789  4    |
| 347-8 f3789   479-8 | 89  5  2   | 6      1    79   |
| 1      2      6     | 4   7 d89  | 359   c3589 359  |
|---------------------+------------+------------------|
| 27     67     3     | 1   4  59  | 8      5679 2579 |
| 9      467-8  478   | 78  2  358 | 357    3567 1    |
| 278    1      5     | 789 6 e389 | 4      379  2379 |
|---------------------+------------+------------------|
| 3458   3459-8 89    | 35  1  7   | 359    2    6    |
| 357    357    12    | 235 9  6   | 157    4    8    |
| 6      3579   12    | 235 8  4   | 13579  3579 3579 |
*-----------------------------------------------------*

X Chain : (8) r1c2 = r1c8 - r3c8 = r3c6 - r6c6 = (8) r2c2 => - 8 r2c13, r57c2

and the solution :

Code: Select all
*-----------------------*
| 7 5 9 | 6 3 1 | 2 8 4 |
| 3 8 4 | 9 5 2 | 6 1 7 |
| 1 2 6 | 4 7 8 | 9 5 3 |
|-------+-------+-------|
| 2 6 3 | 1 4 5 | 8 7 9 |
| 9 4 7 | 8 2 3 | 5 6 1 |
| 8 1 5 | 7 6 9 | 4 3 2 |
|-------+-------+-------|
| 4 9 8 | 5 1 7 | 3 2 6 |
| 5 3 1 | 2 9 6 | 7 4 8 |
| 6 7 2 | 3 8 4 | 1 9 5 |
*-----------------------*

Leren
Leren
 
Posts: 3299
Joined: 03 June 2012

Re: X Sudoku (extreme)

Postby m_b_metcalf » Sat May 19, 2018 10:28 pm

Code: Select all
 . . . . . . . 1 .
 1 2 . . . 9 7 . 6
 . . . . 7 . . . 8
 . . . . . . . . .
 9 . 7 . 8 . 1 . 4
 . . . . . . . . .
 4 . . . 2 . . . .
 8 . 9 5 . . . 3 7
 . 7 . . . . . . .


Even harder (and still symmetric). Have even more fun.
User avatar
m_b_metcalf
2017 Supporter
 
Posts: 9036
Joined: 15 May 2006
Location: Berlin

Re: X Sudoku (extreme)

Postby Leren » Sun May 20, 2018 7:25 am

.......1.12...97.6....7...8.........9.7.8.1.4.........4...2....8.95...37.7.......

Pretty brutal. I had to add diagonal weak links to my solver's forcing chain routines to solve. Anyway here is one X Sudoku move I did see.

Code: Select all
*-----------------------------------------------------------------------*
| 7    345689 34568   |f23468   3456    f234568   | 3459   1      g2359 |
| 1    2      3458    | 348     345      9        | 7      45      6    |
| 356  34569  456     |e12346   7       e123456   | 3459  d2459    8    |
|---------------------+---------------------------+---------------------|
| 2356 134568 1234568 | 1469    134569 ha134567-2 | 35689  256789  2359 |
| 9    356    7       |b236     8       b2356     | 1     c256     4    |
| 2356 134568 1234568 | 1234679 134569   1456     | 35689  256789  2359 |
|---------------------+---------------------------+---------------------|
| 4    1356   1356    | 136789  2        13678    | 569    5689    159  |
| 8    16     9       | 5       146      146      | 2      3       7    |
| 2356 7      12356   | 13689   1369     1368     | 45689  45689   159  |
*-----------------------------------------------------------------------*

X Chain DisContinuous Loop: (2) r4c6 - r5c46 = r5c8 - r3c8 = r3c46 - r1c46 = r1c9 - r4c6 => - 2 r4c6 And the solution, after all those forcing chains

Code: Select all
*-----------------------*
| 7 9 8 | 4 3 6 | 5 1 2 |
| 1 2 3 | 8 5 9 | 7 4 6 |
| 6 5 4 | 1 7 2 | 3 9 8 |
|-------+-------+-------|
| 3 4 5 | 6 1 7 | 8 2 9 |
| 9 6 7 | 2 8 3 | 1 5 4 |
| 2 8 1 | 9 4 5 | 6 7 3 |
|-------+-------+-------|
| 4 3 6 | 7 2 1 | 9 8 5 |
| 8 1 9 | 5 6 4 | 2 3 7 |
| 5 7 2 | 3 9 8 | 4 6 1 |
*-----------------------*

Leren
Leren
 
Posts: 3299
Joined: 03 June 2012


Return to Sudoku variants