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 Post subject: Pinata Killer Sudoku 43
PostPosted: Sun Aug 11, 2013 9:07 am 
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Pinata Killer Sudoku 42 Solution:
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Pinata Killer Sudoku 43
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Jsudoku Code: 3x3::k:3328:3328:5121:3330:3330:7427:3332:2821:5382:3328:5121:5121:3330:7427:7427:3332:2821:5382:1287:4360:5121:7427:7427:3081:5130:5130:5382:1287:4360:4360:7435:7435:3081:5130:5382:5382:2572:2572:5645:7435:7435:7435:5130:3854:3854:8207:8207:5645:4112:7435:7435:2065:2065:2578:8207:5645:5645:4112:5395:5395:5908:2065:2578:8207:2581:1558:5395:5395:3863:5908:5908:3608:8207:2581:1558:5395:3863:3863:5908:3608:3608:

Sudoku Solver Score: 1.25


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PostPosted: Thu Aug 15, 2013 2:32 am 
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Joined: Wed Apr 23, 2008 6:04 pm
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Location: Lethbridge, Alberta, Canada
I'm getting ready to go on holiday so thanks Pinata for posting a fairly easy killer! :)

It starts easily with many cages quickly reducing to one combination; then there's a "sting in the tail". I'll be interested to see whether anyone finds a better way to make the final breakthroughs.

Here is my walkthrough for Pinata Killer #43:
Prelims

a) R12C7 = {49/58/67}, no 1,2,3
b) R12C8 = {29/38/47/56}, no 1
c) R34C1 = {14/23}
d) R34C6 = {39/48/57}, no 1,2,6
e) R5C12 = {19/28/37/46}, no 5
f) R5C89 = {69/78}
g) R67C4 = {79}
h) R67C9 = {19/28/37/46}, no 5
i) R89C2 = {19/28/37/46}, no 5
j) R89C3 = {15/24}
k) 8(3) cage at R6C7 = {125/134}
l) 32(5) at R6C1 = {26789/35789/45689}, no 1
m) 29(7) cage at R4C4 = {1234568}, no 7,9

1. 45 rule on N2 1 innie R3C6 = 3, R4C6 = 9, R6C4 = 7, R7C4 = 9, clean-up: no 2 in R4C1, no 1 in R6C9, no 3 in R7C9

CPEs resulting from Prelims
2a. 32(5) at R6C1 = {26789/35789/45689}, no 8,9 in R5C1, clean-up: no 1,2 in R5C2
2b. 8(3) cage at R6C7 = {125/134}, no 1 in R4C8

3. 45 rule on N1 2 innies R3C12 = 12 = [48], R4C1 = 1, clean-up: no 2 in R5C1, no 6,9 in R5C2, no 2 in R89C2
3a. Killer pair 6,7 in R5C12 and R5C89, locked for R5

4. R3C2 = 8 -> R4C23 = {27/45} (cannot be {36} which clashes with R5C12), no 3,6
4a. Killer pair 4,7 in R4C23 and R5C12, locked for N4

5. 45 rule on N9 2 innies R7C89 = 8 = [17/26], R6C9 = {34}
5a. 9 in N6 only in R5C789, locked for R5

6. 8(3) cage at R6C7 = {125} (only remaining combination, cannot be {134} which clashes with R6C9), 5 locked for R6 and N6
6a. 8(3) cage = {125}, CPE no 2 in R4C8

7. 13(3) cage at R1C1 = {139/157/256}
7a. 1 of {139/157} must be in R1C2 -> no 7,9 in R1C2

8. 13(3) cage at R1C4 = {148/157/247/256}, no 9

9. 45 rule on C1 3 outies R156C2 = 15 = {249/267/357/456} (cannot be {159} because 1,5 only in R1C2), no 1
9a. 3 of {357} must be in R6C2 -> no 3 in R15C2, clean-up: no 7 in R5C1

10. 13(3) cage at R1C1 (step 7) = {256} (only remaining combination), locked for N1
10a. 3 in C1 only in R56789C1, CPE no 3 in R6C2

11. 45 rule on C1 2 outies R16C2 = 1 innie R5C1 + 5
11a. R5C1 = {36} -> R16C2 = 8,11 = {26}/[29] (cannot be [56] which clashes with R5C1), no 5, 2 locked for C2, clean-up: no 7 in R4C3 (step 4)
11b. Naked triple {256} in 13(3) cage at R1C1, 5 locked for C1

12. 32(5) at R6C1 = {26789} (only remaining combination), no 3

13. R5C1 = 3 (hidden single in C1), R5C2 = 7, clean-up: no 2 in R4C3 (step 4), no 8 in R5C89, no 3 in R89C2
13a. Naked pair {45} in R4C23, locked for R4 and N4
13b. Naked pair {69} in R5C89, locked for N6
13c. Killer pair 1,4 in R89C2 and R89C3, locked for N7
13d. 7 in C1 only in R789C1, locked for N7

14. R156C2 (step 9) = {267} (only remaining combination), locked for C2, clean-up: no 4 in R89C2
14a. Naked pair {19} in R89C2, locked for C2 and N7 -> R2C2 = 3, clean-up: no 8 in R1C8, no 5 in R89C3
14b. Naked pair {24} in R89C3, locked for C3 and N7 -> R4C23 = [45], R5C3 = 8

15. 22(4) cage at R5C3 = {3568} (only remaining combination) -> R6C3 = 6, R6C12 = [92], R7C23 = [53], R1C2 = 6, clean-up: no 7 in R2C7, no 5 in R2C8
15a. Naked pair {15} in R6C78, locked for R6, N6 and 8(3) cage at R6C7 -> R7C8 = 2, R7C9 = 6 (step 5), R6C9 = 4, R6C56 = [38], R5C89 = [69], clean-up: no 5,9 in R1C8, no 9 in R2C8
15b. Naked pair {26} in R4C45, locked for R4 and N5

16. R5C7 = 2 -> 20(4) cage at R3C7 = {1289/2369/2567} (cannot be {2378} because 3,8 only in R4C7)
16a. 7 of {2567} must be in R4C7 -> no 7 in R3C78

17. 21(5) cage at R1C9 = {12378} (only remaining combination), no 5, 1 locked for C9 and N3
17a. 5 in C9 only in 14(3) cage at R8C9 = {158} (only remaining combination) -> R9C8 = 1, R89C9 = {58}, locked for C9 and N9, R6C78 = [15], R3C8 = 9, R89C2 = [19], clean-up: no 4 in R12C7
17b. 21(5) cage = {12378} -> R4C8 = 8, clean-up: no 3 in R1C8
17c. Naked pair {47} in R12C8, locked for C8 and N3 -> R8C8 = 3
17d. Naked pair {12} in R23C9, locked for C9 -> R1C9 = 3, R4C9 = 7, R4C7 = 3, R3C7 = 6 (cage sum)
17e. 5 in R3 only in R3C45, locked for N2

18. R2C5 = 9 (hidden single in N2)
18a. 8 in N4 only in 13(3) cage at R1C4 (step 8) = {148} (only remaining combination), locked for N2
18b. R2C6 = 6 (hidden single in N2)

19. 15(3) cage at R8C6 = {258/456} (cannot be {267} which clashes with R1C6), no 7, 5 locked for N8
19a. 6,8 only in R9C5 -> R9C5 = {68}
19b. 15(3) cage = {258/456}, 5 locked for C6

20. R1C3 = 9 (hidden single in N1), R8C7 = 9 (hidden single in N9), R9C4 = 3 (hidden single in N8)
20a. 1 in R1 only in R1C45, locked for N2

[The final breakthrough steps were the hardest ones to find.]
21. 45 rule on R89 2 remaining outies R7C17 = 2 remaining innies R8C45 + 2
21a. R7C17 = [74/84] (cannot be [87] = 15 because R8C45 = 13 = [67] clashes with R8C1 = {67} when R7C1 = 8) -> R7C7 = 4, R9C7 = 7
21b. Naked pair {68} in R9C15, locked for R9 -> R89C9 = [85]
21c. R7C17 = [74/84] = 11,12 -> R8C45 = 9,10 = [27/46/64], no 2 in R8C5
21d. R8C6 = 5 (hidden single in N8)

22. 1,3,7 in N8 only in 21(5) cage at R7C5 = {13467} (only remaining combination, cannot be {12378} which clashes with R58C6, killer ALS block) -> R7C56 = {17}, locked for R7, R8C45 = {46}, locked for R8 and N8, R9C56 = [82]

and the rest is naked singles.

Rating Comment:
I'll rate my walkthrough for Pinata #43 at Hard 1.25; the two final steps feel a bit more than 1.25.

I'll be away until early September, with no internet access.

I hope that Ed, Pinata and maybe others will post Assassins and other killers while I'm away, and that at least one walkthrough will be posted for each puzzle posted. I'll try them after I return home.


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PostPosted: Thu Aug 15, 2013 7:56 pm 
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I am glad that you enjoyed the puzzle and have a nice holiday.


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PostPosted: Sun Aug 18, 2013 4:01 am 
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Joined: Wed Apr 16, 2008 1:16 am
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Location: Sydney, Australia
Really nice puzzle, thanks Pinata! Like Andrew found the end has a real sting. Had to think long and hard. Andrew found a short-cut way to finally crack it. Here's my way.

PKS 43 Alt ending
Download attached file to end of Andrew's step 20: then open from your computer
Or paste candidates into SS once PKS43 is open:
.-------------------------------.-------------------------------.-------------------------------.
| 25 6 9 | 148 148 27 | 58 47 3 |
| 25 3 17 | 48 9 6 | 58 47 12 |
| 4 8 17 | 25 257 3 | 6 9 12 |
:-------------------------------+-------------------------------+-------------------------------:
| 1 4 5 | 26 26 9 | 3 8 7 |
| 3 7 8 | 145 145 14 | 2 6 9 |
| 9 2 6 | 7 3 8 | 1 5 4 |
:-------------------------------+-------------------------------+-------------------------------:
| 78 5 3 | 9 1478 147 | 47 2 6 |
| 678 1 24 | 2468 24678 245 | 9 3 58 |
| 678 9 24 | 3 68 245 | 47 1 58 |
'-------------------------------.-------------------------------.-------------------------------'
6 steps:
21. 21(5)r7c5 = {12378/13467}
21a. cannot have both 6 & 8
21b. 6 & 7 in r8 in r8c145 -> no 8 in r7c5 since it forces 6 & 7 in r8 into r8c1(Locking-out cages)

22. 21(5)r7c5 = {12378/13467}
22a. focussing on 2 & 8 in {12378}: [82] in r78c5 blocked by r49c5 = two of {268}(Almost Locked Set (ALS) Block)
22b. [82] in r8c45 blocked by r8c369 = three of {2458} (ALS Block)
22c. -> no 2 in r8c5

23. 21(5)r7c5 = {12378/13467}
23a. focussing on 7 in r7c6: r789c6 must have one of 1 or 4 for c6 (Hidden killer pair) -> 7 in r7c6 as [7]{1346} blocked (Richard's solver calls this type of step Hidden Killer Mutuals)
23b. and [7]{1238} has no 1,2 nor 8 in r7c5
23c. -> no 7 in r7c6

24. Hidden single 7 in c6 -> r1c6 = 7

25. Naked pair {14} in r57c6: 4 locked for c6

26. Naked pair {25} in r89c6: 2 locked for n8
26a. r89c6 = {25} = 7 -> r9c5 = 8 (cage sum)

Naked singles from there.
Cheerio
Ed


Attachments:
P43 andrew WT to end step 20.ssv [117.05 KiB]
Downloaded 820 times
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PostPosted: Sun Aug 18, 2013 1:51 pm 
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Andrew wrote:
I'm getting ready to go on holiday so thanks Pinata for posting a fairly easy killer! :)

It starts easily with many cages quickly reducing to one combination; then there's a "sting in the tail".

UGGHH!! Just when I thought this might be one I could try!


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