Hi urhegyi,
urhegyi wrote:help.png
Can someone on this forum find help me to find another way of solving this sudoku which is less difficult. Perhaps I didn't saw a logical step and made it to complicated?
It's not a trivial puzzle, as it probably requires several steps even from a decent player. Not very difficult ones, though. (Disclaimer: I don't have time to solve it manually, so I just used Hodoku to analyze it a bit). Hodoku claims it can solve it in a single step but it requires such a horrible net that I'm not willing to verify it (Hodoku's net solutions aren't always reliable, so I have my doubts). In any case, Hodoku's default path (with my settings) takes 12 steps (of which some are most likely unnecessary, but I haven't checked which ones):
- 2-String Kite: -1 r4c2
- 2-String Kite: -8 r3c2
- AIC[5]: -2 r1c7,r78c9 -> basics, 3 singles
- AIC[5]: -5 r1c2
- AIC[4]: -6 r3c6
- AIC[4]: -1 r6c7
- AIC[4]: -8 r6c2
- ALS-AIC[5]: -6 r2c6 (*) -> pointing pair
- XY-Chain[8]: -8 r5c6,r6c3 -> 5 singles
- W-Wing: -6 r4c2
- W-Wing: -6 r6c4 -> 10 singles, pointing pair
- XY-Wing: -9 r2c2,r9c3; stte
All but one of those steps are short and basic AICs. Only step 8 is a bit complicated because it uses two relatively big ALSs. Still, it's a normal AIC too. (Btw, you have to turn on "Preferences::Steps::Allow ALS in chains" for Hodoku to find it. For some weird reason it's not on by default.)
So, no need for kraken fishes or other complicated techniques. (I haven't seen that a kraken fish is ever
needed anyway, and very few human players would use them at all. Normal krakens (which Hodoku calls "Forcing Chain Verity") that use cells, rows, columns, or boxes, are usually simpler and in my experience almost always find the same eliminations.)
(*) Here's the most complicated step 8:
- Code: Select all
.-------------------.--------------------.-------------.
| 1 f79 f579 | 4 59 a[6]8 | b68 3 2 |
| 3 f89(6) f89(6) | 29 1 28-6 | 7 4 5 |
| 2 456 4568 | 7 3568 38 | c168 9 16 |
:-------------------+--------------------+-------------:
| 4 356 e156 | e29 e69 e126 | d135 7 8 |
| 9 58 2 | 13 7 48 | 45 6 13 |
| 7 136 168 | 136 48 5 | 34 2 9 |
:-------------------+--------------------+-------------:
| 6 2 17 | 5 34 134 | 9 8 47 |
| 8 17 3 | 16 46 9 | 2 5 47 |
| 5 49 49 | 8 2 7 | 36 1 36 |
'-------------------'--------------------'-------------'
(6=8)r1c6 - r1c7 = (8-1)r3c7 = r4c7 - (1=269'5)r4c6543 - (5=798'6)b1p2356 => -6 r2c6
Or with the last node broken into two pieces:
(6=8)r1c6 - r1c7 = (8-1)r3c7 = r4c7 - (1=2695)r4c6543 - (5=79)r1c23 - (9=86)r2c23 => -6 r2c6
--
I also tried to find a shorter path with krakens (but not nets). A pretty reasonable one takes five steps with 3 simple AICs (one ALS) and 2 relatively simple krakens (cell and row):
1) ALS XY-Wing: (6=8)r1c6 - (8=4)r5c6 - (4=136)r539c9 => -6 r1c9 (-> 3 singles)
2) Kraken Cell (168)r6c3 => -4 r6c5 (-> 2 singles)
- Code: Select all
(1)r6c3 - (1=7)r7c3 - (7=4)r7c9
||
(6)r6c3 - r6c4 = r8c4 - (6=4)r8c5
||
(8)r6c3 - (8=4)r6c5
=> -4 r6c5
3) AIC[5]: (5=8)r5c2 - (8=4)r5c6 - (4=1)r7c6 - (1=7)r7c3 - r1c3 = (7)r1c2 => -5 r1c2
4) Kraken Row (5r3) => -9 r1c2 (-> 13 singles)
- Code: Select all
(5)r3c2 - (5=8)r5c2 - (8=4)r5c6 - (4=1)r7c6 - (1=7)r7c3 - r1c3 = (7)r1c2
||
(5-4)r3c3 = r3c2 - (4=9)r9c2
||
(5)r3c5 - (5=9)r1c5
=> -9 r1c2
5) XY-Chain[4]: (6=9)r2c2 - (9=5)r1c3 - (5=1)r4c3 - (1=6)r6c3 => -6 r23c3,r6c2; stte
--
Does that give you new ideas at all?