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 Post subject: Assassin 214
PostPosted: Fri Jun 10, 2011 8:40 am 
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Grand Master
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Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
Had a terrible time trying to find a decent puzzle with this cage pattern. I was originally planning to have this pattern for Easter. Won't do symetrical again! ;)

I found this version quite resistant till a variant move revealed itself. Am sure SudokuSolver can't do it so there must be a conventional way. Turns out, it can be cracked much quicker than recent puzzles (comparing my optimised solutions).

If anyone wants another (harder?) one, please ask. I have one I couldn't solve but would love to know how.

Assassin 214

Image

Code; paste into solver:
3x3::k:4865:3586:3586:3586:7171:3844:3844:3844:2821:4865:3846:3846:3846:7171:6663:6663:6663:2821:4865:5384:3846:7171:7171:7171:6663:8457:2821:5384:5384:5384:2058:7171:1291:8457:8457:8457:1804:5384:7693:2058:3598:1291:5647:8457:2832:1804:7693:7693:7693:3598:5647:5647:5647:2832:8977:8977:7693:3346:3346:3346:5647:6163:6163:3348:8977:1557:1557:2326:3351:3351:6163:3352:3348:8977:8977:8977:2326:6163:6163:6163:3352:
solution:
+-------+-------+-------+
| 9 1 5 | 8 4 7 | 2 6 3 |
| 8 6 3 | 2 1 9 | 4 5 7 |
| 2 7 4 | 3 5 6 | 8 9 1 |
+-------+-------+-------+
| 1 2 6 | 7 9 3 | 5 8 4 |
| 4 5 8 | 1 6 2 | 3 7 9 |
| 3 9 7 | 4 8 5 | 6 1 2 |
+-------+-------+-------+
| 5 8 2 | 9 3 1 | 7 4 6 |
| 6 3 1 | 5 7 4 | 9 2 8 |
| 7 4 9 | 6 2 8 | 1 3 5 |
+-------+-------+-------+
Cheers
Ed


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 Post subject: Re: Assassin 214
PostPosted: Tue Jun 14, 2011 5:06 am 
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Grand Master
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1895
Location: Lethbridge, Alberta, Canada
Many thanks Ed for another challenging Assassin!

It's interesting that you find it hard to create symmetrical Assassins. I like them because when I spot a relationship in one part of the grid pattern, I look for another in the corresponding area (I guess that must be my methodical approach to solving); of course that one may not be useful, depending on what the cage totals are. I'm equally happy with asymmetrical cage patterns; just have to think a bit harder.

Ed wrote:
I found this version quite resistant till a variant move revealed itself.
Don't think I did that, so maybe I found a different way to solve it.

Ed wrote:
If anyone wants another (harder?) one, please ask. I have one I couldn't solve but would love to know how.
Please post it, and the variant you mentioned for A213. I'll have a go at them. I'll do my best to avoid heavy moves.

Rating Comment:
I'll rate my walkthrough for A214 at Hard 1.25. My original walkthrough was harder but while checking I found a flawed step. I re-worked from that stage, moving forward a step which I'd used later, and was happy to find that it gave a simpler solving path.

Here is my walkthrough for A214:
Prelims

a) R45C4 = {17/26/35}, no 4,8,9
b) R45C6 = {14/23}
c) R56C1 = {16/26/34}, no 7,8,9
d) R56C5 = {59/68}
e) R56C9 = {29/38/47/56}, no 1
f) R89C1 = {49/58/67}, no 1,2,3
g) R8C34 = {15/24}
h) R89C5 = {18/27/36/45}, no 9
i) R8C67= {49/58/67}, no 1,2,3
j) R89C9 = {49/58/67}, no 1,2,3
k) 19(3) cage at R1C1 = {289/379/469/478/578}, no 1
l) 11(3) cage at R1C9 = {128/137/146/236/245}, no 9
m) 26(4) cage at R2C6 = {2789/3689/4589/4679/5678}, no 1
n) 33(5) cage at R3C8 = {36789/45789}, no 1,2

Step resulting from Prelims
1. 33(5) cage at R3C8 = {36789/45789}, CPE no 7,8,9 in R6C8

2. 45 rule on C1 2 innies R47C1 = 6 = {15/24}
2a. R56C1 = {16/34} (cannot be {25} which clashes with R478C1), no 2,5
2b. Killer pair 1,4 in R47C1 and R56C1, locked for C1, clean-up: no 9 in R89C1

3. 9 in C1 only in 19(3) cage at R1C1, locked for N1
3a. 19(3) cage = {289/379}, no 5,6
3b. 15(4) cage at R2C2 = {1248/1257/1347/1356/2346} (cannot be {1239} = {123}9 which clashes with 19(3) cage at R1C1), no 9

4. 45 rule on C9 2 innies R47C9 = 10 = {37/46}/[82/91], no 5, no 8,9 in R7C9

5. 45 rule on R789 2 innies R7C37 = 9 = {18/27/36/45}, no 9
5a. 9 in N7 only in R789C2 + R9C3, locked for 35(6) cage at R7C1, no 9 in R9C4

6. 45 rule on C1234 2 innies R37C4 = 12 = {39/48/57}, no 1,2,6

7. 45 rule on C6789 2 innies R37C6 = 7 = {16/25} (cannot be {34} which clashes with R45C6)
7a. Killer pair 1,2 in R37C6 and R45C6, locked for C6

8. 45 rule on N7 1 outie R9C4 = 2 innies R78C3 + 3
8a. Min R78C3 = 3 -> min R9C4 = 6
8b. Max R9C4 = 8 -> max R78C3 = 5, no 5,6,7,8 in R7C3, no 5 in R8C3, clean-up: no 1,2,3,4 in R7C7 (step 5), no 1 in R8C4

9. 35(6) cage at R7C1 must contain both of 8,9, CPE no 8 in R9C1, clean-up: no 5 in R8C1

10. 1,2,3 in N9 only in R7C89 + R8C8 + R9C78, locked for 24(6) cage at R7C8, no 3 in R9C6

11. 45 rule on N6 3 innies R5C7 + R6C78 = 1 outie R3C8 + 1
11a. Min R5C7 + R6C78 = 6 -> min R3C8 = 5
11b. Max R5C7 + R6C78 = 10, no 8,9 in R56C7
11c. Max R5C7 + R6C78 = 10 -> min R6C6 + R7C7 = 12, no 3 in R6C6

12. 45 rule on N5 3 innies R4C5 + R6C46 = 18 = {279/378/459/468} (cannot be {189/369/567} which clash with R56C5), no 1

13. R37C6 (step 7) = 7 = {16/25}, R45C6 = 5 = {14/23} -> combined cage R3457C6 = 12 = {1236/1245}
[Or for those who don’t like combined cages ;-)
45 rule on C6789 4 innies R3456C6 = 12 = {1236/1245}]
13a. 45 rule on N9 2 outies R89C6 = 1 innie R7C7 + 5
13b. Min R89C6 = 11 (R89C6 cannot be {46} = 10 which clashes with R3457C6) -> min R7C7 = 6, clean-up: no 4 in R7C3 (step 5)

14. 30(5) cage at R5C3 cannot contain more than one of 1,2,3
14a. R7C3 = {123} -> no 1,2,3 in R5C3 + R6C234
14b. 2 in N4 only in R4C123 + R5C2, locked for 21(5) cage at R3C2, no 2 in R3C2

15. 45 rule on N89 3(2+1) innies R7C7 + R89C4 = 18
15a. Max R7C7 = 8 -> min R89C4 = 10
15b. 45 rule on N8 4 innies R89C46 = 23 = {2489/2678/4568} (cannot be {2579} because min R89C4 = 10), 8 locked for N8, clean-up: no 4 in R3C4 (step 6), no 1 in R89C5

16. 1 in N8 only in 13(3) cage at R7C4, locked for R7, clean-up: no 5 in R4C1 (step 2), no 9 in R4C9 (step 4), no 8 in R7C7 (step 5)
16a. 13(3) cage = {139/157}, no 2,4,6, clean-up: no 8 in R3C4 (step 6), no 1,5 in R3C6 (step 7)
16b. R89C9 = {49/58} (cannot be {67} which clashes with R7C7), no 6,7

17. 1 in C9 only in 11(3) cage at R1C9, locked for N3
17a. 11(3) cage = {128/137/146}, no 5

18. 45 rule on N36 4(3+1) outies R126C6 + R7C7 = 28
18a. Max R7C7 = 7 -> min R126C6 = 21, no 3 in R12C6

19. 3 in C6 only in R45C6 = {23}, locked for C6 and N5 -> R3C6 = 6, R7C6 = 1 (step 7), clean-up: no 5,6 in R45C4, no 7 in R8C7
19a. Naked pair {17} in R45C4, locked for C4 and N5, clean-up: no 5 in R37C4 (step 6)
19b. Naked pair {39} in R37C4, locked for C4

20. 13(3) cage at R7C4 (step 16a) = {139} (only remaining combination, cannot be {157} because 5,7 only in R7C5), 3,9 locked for R7 and N8 -> R7C3 = 2, R7C7 = 7 (step 5), clean-up: no 4 in R4C1 (step 2), no 3,7,8 in R4C9 (step 4), no 4 in R8C7, no 6 in R89C5

21. Naked pair {46} in R47C9, locked for C9, clean-up: no 5,7 in R56C9, no 9 in R89C9
21a. Naked pair {58} in R89C9, locked for C9 and N9, clean-up: no 5,8 in R8C6

22. Naked pair {46} in R7C89, locked for R7 and N9 -> R7C1 = 5, R4C1 = 1 (step 2), R7C2 = 8, R45C4 = [71], R8C7 = 9, R8C6 = 4, R8C3 = 1, R8C4 = 5, R89C5 = [85], clean-up: no 6 in R56C1, no 3 in R56C9
22a. Naked pair {34} in R56C1, locked for C1 and N4
22b. Naked pair {29} in R56C9, locked for C9 and N6

23. R9C4 = 6 -> R89C1 = [67], R8C2 = 3, R8C8 = 2, R89C5 = [72], R9C6 = 8
[Step 23 simplified. When I first solved this puzzle I must have forgotten to manually eliminate 8 from R9C4 in step 22.]

24. Naked triple {289} in 19(3) cage at R1C1, locked for N1

25. Naked triple {137} in 11(3) cage at R1C9, locked for N3

26. 33(5) cage at R3C8 must contain 9 -> R3C8 = 9, R4C4 = 3, R7C45 = [93]

27. 28(6) cage at R1C5 must contain 1,3,6 = {134569} (only remaining combination), no 8

28. R56C5 = {68} (hidden pair in C5), locked for N5 -> R6C4 = 4, R56C1 = [43]

29. 26(4) cage at R2C6 = {4589/5678} (cannot be {2789} because 7,9 only in R2C6), no 2, 8 locked for N3
29a. 7,9 only in R2C6 -> R2C6 = {79}

30. R1C7 = 2 (hidden single in C7), R12C4 = [82], R123C1 = [982]

31. 15(3) cage at R1C6 = {267} (only remaining combination) -> R1C68 = [76], R2C6 = 9

32. 14(3) cage at R1C2 = {158} (only remaining combination) -> R1C23 = [15]

33. R6C678 = [561], R5C7 = 3, R56C5 = [68]

34. Naked pair {79} in R6C23, locked for R6 and N4 -> R5C3 = 8

35. 15(4) cage at R2C2 (step 3b) = {2346} (only remaining combination) -> R3C3 = 4, R2C2 = 6, R2C3 = 3

and the rest is naked singles.


Last edited by Andrew on Mon Jun 20, 2011 9:47 pm, edited 1 time in total.

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 Post subject: Re: Assassin 214
PostPosted: Sun Jun 19, 2011 10:30 am 
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Grand Master
Grand Master

Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
Thanks Andrew for your WT. Love step 13! However, the key one is step 15 which SudokuSolver can't do. So, there must be at least one other way to solve this. This is the way I did it starting from the end of Andrew's step 12. Thanks to Andrew for some helpful suggestions.

Alt way to crack A214
9 more steps:
.-------------------------------.-------------------------------.-------------------------------.
| 23789 12345678 12345678 | 123456789 123456789 3456789 | 123456789 123456789 12345678 |
| 23789 12345678 12345678 | 12345678 123456789 3456789 | 23456789 23456789 12345678 |
| 23789 12345678 12345678 | 345789 123456789 1256 | 23456789 56789 12345678 |
:-------------------------------+-------------------------------+-------------------------------:
| 1245 123456789 123456789 | 123567 23456789 1234 | 3456789 3456789 346789 |
| 1346 123456789 123456789 | 123567 5689 1234 | 1234567 3456789 23456789 |
| 1346 123456789 123456789 | 23456789 5689 456789 | 1234567 123456 23456789 |
:-------------------------------+-------------------------------+-------------------------------:
| 1245 123456789 1234 | 345789 123456789 1256 | 5678 123456789 123467 |
| 678 123456789 124 | 245 12345678 456789 | 456789 123456789 456789 |
| 567 123456789 123456789 | 678 12345678 456789 | 123456789 123456789 456789 |
'-------------------------------.-------------------------------.-------------------------------'


Andrew's end of step 12 above.
13. 13(3)n8 = {139/148/157/238/247/256/346}
13a. note that {139} must {39}[1]
13b. ie 9 in 13(3)n8 ->1 in r7c6 (no eliminations yet)


14. "45" on n9: 2 outies r89c6 - 5 = 1 innie r7c7
14a. max. r7c7 = 8 -> max. r89c6 = 13 = [9 in r89c6 -> 4 in r89c6...] (no eliminations yet)

15. from step 13b & 14a, 9 in n8 in 13(3) or r89c6 -> 1 in r7c6 or 4 in r89c6 = [1/4..]
15a. -> {14} blocked from 5(2)n5 (Blocking cages)

16. 5(2)n6 = {23}: both locked for n5 & c6
16a. 8(2)n5 = {17}: both locked for c4 and n5
16b. h7(2)r37c6 = {16}: both locked for c6
16c. no 5 in h12(2)r37c4
16d. no 7 in r8c7

17. 13(3)n8 must have 1,6 for r7c6 = {139/148/346}(no 2,5,7)({157/256} blocked by none in r7c4)
17a. = [4/9..]

18. "45" on n8: 4 innies r89c46 = 23 and must have one of 6,8 for r9c4
18a. {2489} blocked by 13(3)n8 9 step 17a)
18b. = {2678/4568}(no 9)
18c. must have 6 & 8: both locked for n8
18d. r7c6 = 1
18e. r3c6 = 6
18f. no 5 in r4c1 (h6(2)r47c1)
18g. no 8 in r7c7 (h9(2)r7c37)
18h. no 3 in 9(2)n8

19. 3 & 9 only in 13(3)n8 = {39}[1]: 3 and 9 locked for r7
19a. h12(2)r37c4 = {39}: both locked for c4
19b. no 6 in r7c7 (h9(2)r7c37)
19c. no 4 in r8c7

20. from step 14 r89c6 - 5 = r7c7
20a. r7c7 = (57) -> r89c6 = 10/12
20b. but r89c6 can't sum to 10 -> = 12 only = {48/57} = [4/5..]
20c. -> r7c7 = 7
20d. r7c3 = 2 (h9(2)r7c37)
20e. no 4 in r8c4

21. 9(2)n8: {45} blocked by r89c6 (step 20b)
21a. = {27} only: both locked for c5 & n8

cracked.
Cheers
Ed


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