Code: Select all
.------------------.------------------.------------------.
| 2 A34 7 | 6 -3489 489 | 5 1 D38 |
| 68 13-45 45 | 23 12348 7 | 9 46 23-8 |
| 68 13-4 9 | 5 12348 1248 | 28 46 7 |
:------------------+------------------+------------------:
| 5 6 2 | 19 179 3 | 178 89 4 |
| 79 8 13 | 4 5 6 | 127 239 129 |
| 4 79 13 | 8 1279 129 | 6 39 5 |
:------------------+------------------+------------------:
| 1 79 6 | 23 2389 5 | 4 2789 C289 |
| 3 B45 8 | 7 6 249 |C12 C259 C129 |
| 79 2 45 | 19 1489 1489 | 3 578 6 |
'------------------'------------------'------------------'
(3=4)r1c2 - (4=5)r8c2 - (5=1298)r7c9|r8c789 - (8=3)r1c9 - (3=4)r1c2
The ring gives eliminations of (4)r23c2, (8)r2c9, and (3)r1c5. After these eliminations and basic follow-up the grid looks like this:
Code: Select all
.------------------.------------------.------------------.
| 2 34 7 | 6 *489 *489 | 5 1 *38 |
| 68 15 45 | 23 148 7 | 9 46 *23 |
|*68 13 9 | 5 123-48 12-48 |*28 *46 7 |
:------------------+------------------+------------------:
| 5 6 2 | 19 179 3 | 178 89 4 |
| 79 8 13 | 4 5 6 | 127 239 129 |
| 4 79 13 | 8 1279 129 | 6 39 5 |
:------------------+------------------+------------------:
| 1 79 6 | 23 2389 5 | 4 2789 289 |
| 3 45 8 | 7 6 249 | 12 259 129 |
| 79 2 45 | 19 1489 1489 | 3 578 6 |
'------------------'------------------'------------------'
(4=682)r3c178 - (2=38)r12c9 - (8=94)r1c56 => r3c56 <> 4
This leaves r3c8 as the only cell with a "4" candidate in row 3. Following up we reach:
Code: Select all
.---------------.---------------.---------------.
| 2 34 7 | 6 489 489 | 5 1 38 |
| 8 15 45 | 23 14 7 | 9 6 23 |
| 6 13 9 | 5 1238 128 | 28 4 7 |
:---------------+---------------+---------------:
| 5 6 2 | 19 179 3 | 178 89 4 |
|#79 8 13 | 4 5 6 |*12+7 239 *12+9|
| 4 #79 13 | 8 1279 129 | 6 39 5 |
:---------------+---------------+---------------:
| 1 #79 6 | 23 2389 5 | 4 2789 28-9|
| 3 45 8 | 7 6 249 |*12 259 *12+9|
| 79 2 45 | 19 1489 1489| 3 578 6 |
'---------------'---------------'---------------'
(9=12)r58c9 - UR - (12=7)r58c7 - (7=9)r5c1 - (9=7)r6c2 - (7=9)r7c2 => r7c9 <> 9
With r7c9 reduced to "28", there is now a naked "238" triple in r127c9. Following up, we find an X-wing for digit "2" in r27c49, eliminating (2)r7c58, and an XY wing eliminating (3)r6c3:
(3=1)r5c3 - (1=9)r5c9 - (9=3)r6c8 => r6c3 <> 3
This brings us to:
Code: Select all
.---------------.---------------.------------------.
| 2 34 7 | 6 489 489 | 5 1 38 |
| 8 15 45 | 23 14 7 | 9 6 23 |
| 6 13 9 | 5 1238 128 | 28 4 7 |
:---------------+---------------+------------------:
| 5 6 2 | 19 179 3 | 78 89 4 |
| 79 8 3 | 4 5 6 |*12+7 *29 *19 |
| 4 79 1 | 8 279 29 | 6 3 5 |
:---------------+---------------+------------------:
| 1 79 6 | 23 389 5 | 4 789 28 |
| 3 45 8 | 7 6 249 |*12 *29+5 *19 |
| 79 2 45 | 19 1489 1489| 3 578 6 |
'---------------'---------------'------------------'
(5=129)r8c789 - DP - (129=7)r5c789 - (7=8)r4c7 - (8=295)r458c8 => r8c8=5
and this is enough to complete the solution easily. By comparison, from the position above the Sudocue solver uses (not in order) a Nishio step, three XY chains, a naked quad, and an XY wing to complete the solution.