This puzzle is published in the sample section of "Solving Sudoku" document by Michael Mepham. It´s rated tough, but even with the "diabolical" in the same section I was luckier.
. . 1|9 . .|. . 8
6 . .|. 8 5|. 3 .
. . 7|. 6 .|1 . .
-----+-----+-----
. 3 4|. 9 .|. . .
. . .|5 . 4|. . .
. . .|. 1 .|4 2 .
-----+-----+-----
. . 5|. 7 .|9 . .
. 1 .|8 4 .|. . 7
7 . .|. . 9|2 . .
After using some basic techniques and finned x-wing I arrive to
.------------------.------------------.------------------.
| 2345 245 1 | 9 23 7 | 56 456 8 |
| 6 249 29 | 1 8 5 | 7 3 249 |
| 23589 2589 7 | 4 6 23 | 1 59 259 |
:------------------+------------------+------------------:
| 1258 3 4 | 267 9 268 | 568 1567 156 |
| 1289 26789 2689 | 5 23 4 | 368 1679 1369 |
| 589 56789 689 | 367 1 368 | 4 2 3569 |
:------------------+------------------+------------------:
| 248 2468 5 | 236 7 1 | 9 48 36 |
| 29 1 2369 | 8 4 236 | 356 56 7 |
| 7 468 368 | 36 5 9 | 2 148 14 |
'------------------'------------------'------------------'
Here I am stuck! Any ideas?
I am stuck
I can help you a little. When SudoCue reports a template check, I check for a Nishio style trick.
here it is:
Either R1C5 or C3C6 = 2.
When R1C5=2, R1C1 cannot be 2.
When R3C6=2, R7C4=2, R5C5=2, R4C1=2, R1C1 cannot be 2.
In both cases, R1C1 cannot be 2.
The next step must include a forcing chain or nice loop. I cannot find a simple one. Maybe one of our forum members can help us here.
Ruud
here it is:
Either R1C5 or C3C6 = 2.
When R1C5=2, R1C1 cannot be 2.
When R3C6=2, R7C4=2, R5C5=2, R4C1=2, R1C1 cannot be 2.
In both cases, R1C1 cannot be 2.
The next step must include a forcing chain or nice loop. I cannot find a simple one. Maybe one of our forum members can help us here.
Ruud
-
- Regular
- Posts: 14
- Joined: Tue May 30, 2006 8:07 pm
Code: Select all
+----------------------+----------------------+----------------------+
| 2345 245 1 | 9 23 7 | 56 456 8 |
| 6 249 29 | 1 8 5 | 7 3 249 |
| 23589 2589 7 | 4 6 23 | 1 59 259 |
+----------------------+----------------------+----------------------+
| 1258 3 4 | 267 9 268 | 568 1567 156 |
| 1289 26789 2689 | 5 23 4 | 368 1679 1369 |
| 589 56789 689 | 367 1 368 | 4 2 3569 |
+----------------------+----------------------+----------------------+
| 248 2468 5 | 236 7 1 | 9 48 36 |
| 29 1 2369 | 8 4 236 | 356 56 7 |
| 7 468 368 | 36 5 9 | 2 148 14 |
+----------------------+----------------------+----------------------+
[r7c4]=3=[r7c9]-3-[r8c7]=3=[r5c7]-3-[r5c5]-2-[r4c4]=2=[r7c4] => r7c4=23
[r7c1]=4=[r1c1]=3=[r1c5]=2=[r5c5]-2-[r4c4]=2=[r7c4]-2-[r7c1] => r7c1<>2
XY-wing (236): r7c24,r9c4 => r9c23<>6
X-wing in 3's: r67c49 => r5c9<>3
Coloring in 2's: r1c25,r7c24,r4c4,r5c5 => r235c2<>2
Coloring in 2's: r1c25,r2c3,r5c5 => r5c3<>2
Code: Select all
+-------------------+-------------------+-------------------+
| 34 245 1 | 9 23 7 | 56 456 8 |
| 6 49 29 | 1 8 5 | 7 3 249 |
| 38 589 7 | 4 6 23 | 1 59 259 |
+-------------------+-------------------+-------------------+
| 12 3 4 | 27 9 68 | 568 1567 156 |
| 12 679 689 | 5 23 4 | 368 1679 169 |
| 5 679 689 | 37 1 68 | 4 2 369 |
+-------------------+-------------------+-------------------+
| 48 26 5 | 23 7 1 | 9 48 36 |
| 9 1 26 | 8 4 23 | 356 56 7 |
| 7 48 3 | 6 5 9 | 2 148 14 |
+-------------------+-------------------+-------------------+