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 Post subject: Assassin 277
PostPosted: Fri Nov 29, 2013 4:10 pm 
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Grand Master
Grand Master

Joined: Wed Apr 30, 2008 9:45 pm
Posts: 694
Location: Saudi Arabia
Assassin 277


I have not posted an assassin for a while so tried some cage merges on a random generated one, SS gives it 1.5 and JS uses a couple of little fishes - so it seems about right.


Image
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JS Code:
3x3:d:k:3841:3841:3586:3075:3075:3332:3332:6430:6430:3841:3841:3586:3586:1286:1286:3615:6430:6430:8981:8981:8981:8981:6666:6666:3615:3615:5910:2316:8981:8981:7693:7693:6666:6666:2574:5910:2316:6164:7952:7693:7693:7693:6666:2574:5910:4370:6164:7952:7952:7693:7693:6428:6428:5910:4370:6164:6164:7952:7952:6428:6428:6428:6428:5395:6164:6164:2327:2327:8733:8733:8733:8733:5395:5395:5395:5395:3355:3355:8733:8733:8733:

Solution:

126579483
487123659
395864172
264318597
758492316
913756248
832941765
549637821
671285934


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 Post subject: Re: Assassin 277
PostPosted: Mon Dec 02, 2013 5:33 am 
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Grand Master
Grand Master

Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1894
Location: Lethbridge, Alberta, Canada
Thanks HATMAN for posting another Assassin!

My solving path was fairly short, with one heavy step. No fishes or forcing chains.

Here is my walkthrough for Assassin 277:
Prelims

a) R1C45 = {39/48/57}, no 1,2,6
b) R1C67 = {49/58/67}, no 1,2,3
c) R2C56 = {14/23}
d) R45C1 = {18/27/36/45}, no 9
e) R45C8 = {19/28/37/46}, no 5
f) R67C1 = {89}
g) R8C45 = {18/27/36/45}, no 9
h) R9C56 = {49/58/67}, no 1,2,3

1. 45 rule on R12 1 innie R2C7 = 6, R3C78 = 8 = {17/35}
1a. 45 rule on N3 2 innies R1C7 + R3C9 = 6 = [42] (cannot be [51] which clashes with R3C78) -> R1C6 = 9, clean-up: no 3,8 in R1C45, no 4 in R9C5

2. Naked pair {57} in R1C45, locked for R1 and N2
2a R1C89 = {18/38} (cannot be {13} which clashes with R3C78), 8 locked for R1 and N3
2b. Killer pair 1,3 in R1C89 and R3C78, locked for N3
2c. 9 in N3 only in R2C89, locked for R2
2d. 2,6 in R1 only in R1C123, locked for N1
2e. 9 in N1 only in R3C123, locked for 35(6) cage at R3C1, no 9 in R4C23

3. R3C9 = 2 -> R456C9 = 21 = {489/678} (cannot be {579} which clashes with R2C9), no 1,3,5, 8 locked for C9 and N6, clean-up: no 2 in R45C8
3a. R1C8 = 8 (hidden single in R1)
3b. R45C8 = {19/37} (cannot be {46} which clashes with R456C9), no 4,6
3c. Killer pair 7,9 in R45C8 and R456C9, locked for N6
3d. Hidden killer pair 4,6 in R6C8 and R456C9 for N6, R456C9 contains one of 4,6 -> R6C8 = {46}
3e. 2,5 in N6 only in R456C7, locked for C7, clean-up: no 3 in R3C8 (step 1)
3f. 9 in C7 only in R789C7, locked for N9
3g. 3 in N3 only in R1C9 + R3C7, locked for D/

4. 45 rule on R89 4 outies R56C2 + R7C23 = 11 = {1235}, locked for 24(6) cage at R5C2, 3 also locked for C2
4a. R56C2 + R7C23 = 11 -> R8C23 = 13 = {49/67}
4b. Naked quad {1235} in R56C2 + R7C23, CPE no 1,2,5 in R9C2

5. Naked pair {89} in R67C1, locked for C1, clean-up: no 1 in R45C1

6. 45 rule on N5 2 innies R4C6 + R6C4 = 15 = [69/78/87]

7. 26(5) cage at R3C5 = {23678/24578/34568} (cannot be {14678} because R45C7 only contain 1,2,3,5), no 1
7a. R45C7 = {235} -> no 3 in R3C56

8. 9 in N4 only in R56C3 + R6C1, CPE no 9 in R6C4, clean-up: no 6 in R3C5 (step 5)
8a. Naked pair {78} in R4C6 + R6C4, locked for N5 and D/, clean-up: no 1 in R3C8 (step 1), no 6 in R8C3 (step 4a)
8b. Naked pair {13} in R1C9 + R3C7, locked for D/
8c. Naked quad {1235} in R56C2 + R7C23, 1 locked for C2

9. 15(4) cage at R1C1 = {1248/1356} (cannot be {1347} because R1C12 must contain one of 2,6, cannot be {1257} which clashes with R2C89, ALS block, cannot be {2346} which clashes with R2C56), no 7, 1 locked for C1 and N1
9a. R1C2 = {26} -> no 2,6 in R1C1
9b. 8 of {1248} must be in R2C2, 5 of {1356} must be in R2C2 -> R2C2 = {58}, no 5 in R2C1
9c. R1C23 = {26} (hidden pair in R1)
9d. Killer pair 2,5 in R12C2 and R567C2, locked for C2
9e. Naked pair {13} in R1C19, CPE no 1,3 in R9C9 using D\

10. Killer triple 5,7,9 in R23C8 and R45C8, locked for C8, 5 also locked for N3

11. 14(3) cage at R1C3 = {167/248/356} (cannot be {158/347} because R1C3 only contains 2,6, cannot be {257} because 5,7 only in R2C3)
11a. R1C3 = {26} -> no 2 in R2C4
11b. 2 in R2 only in R2C56 = {23}, locked for R2 and N2
11c. 14(3) cage = {167/248}, no 5
11d. 1 in N2 only in R23C4, locked for C4, clean-up: no 8 in R8C5

12. 45 rule on N1 4(2+2) outies R23C4 + R4C23 = 19
12a. Max R23C4 = 9 (because 1 must be in R23C4) -> min R4C23 = 10, no 1 in R4C3

13. 45 rule on N1 5 innies R12C3 + R3C123 = 30 = {24789/35679} (cannot be {25689/34689/45678} which clash with 15(4) cage at R1C1)
13a. R12C3 = [24/28/67] -> R3C123 = {359/479/789}

14. 26(5) cage at R3C5 (step 7) = {23678/24578/34568}, R3C7 = {13} -> 26(5) cage + R3C7 = {23678}1/{24578}{13}/{34568}1 [1 and/or 4 in R3]
14a. R3C123 = {359/479/789} = 17,20,24 -> R3C4 + R4C23 = 11,15,18 = {146/168/468} (cannot be {236/245/258} because 2,3,5 only in R4C3, other combinations clash with R3C123), CPE no 6 in R4C4
14b. 35(6) cage at R3C1 = {345689} (only remaining combination, cannot be {146789} = {479}1{68} which clashes with 26(5) cage + R3C7, cannot be {146789} = {789}1{46} which clashes with R45C1 because 7 of {789} must be in R3C1) -> R3C123 = {359}, R3C4 + R4C23 = {468}
[Cracked. The rest is fairly straightforward. Routine clean-ups omitted from here.]

15. R3C2 = 9, R3C13 = {35}, locked for R3 and N1 -> R1C1 = 1, placed for D\, R2C1 = 4, R2C2 = 8, placed for D\, R1C2 = 2 (cage sum), R12C3 = [67], R3C78 = [17], R2C9 = 9, R2C8 = 5, placed for D/, R7C3 = 2, R9C1 = 6, R8C2 = 4, R8C3 = 9, R9C2 = 7, R67C1 = [98]
15a. R45C1 = {27} (hidden pair in C1)

16. R7C7 = 7 (hidden single on D\)
16a. Naked triple {235} in R456C7, locked for C7 and N6 -> R89C7 = [89]
16b. R9C56 = {58} (only remaining combination), locked for R9 and N8 -> R9C9 = 4, placed for D\
16c. R78C9 = {15} (hidden pair in C9), locked for N9

17. R9C3 = 1 (hidden single in R9)
17a. R9C123 = [671] = 14 -> R8C1 + R9C4 = 7 = [52]
17b. R8C45 = {36} (only remaining combination), locked for R8 and N8 -> R8C8 = 2, placed for D\, R8C9 = 1, R8C6 = 7, R4C6 = 8, R6C4 = 7

18. R3C1 = 3, R3C3 = 5, placed for D\
18a. R5C5 = 9 (hidden single on D/)

and the rest is naked singles, without using the diagonals.

Rating Comment:
I'll rate my walkthrough for A277 at 1.5 because of the analysis in step 14, which felt like the sort of step SudokuSolver might find.


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 Post subject: Re: Assassin 277
PostPosted: Tue Dec 03, 2013 10:28 am 
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Grand Master
Grand Master

Joined: Wed Apr 16, 2008 1:16 am
Posts: 1043
Location: Sydney, Australia
Wonderfully efficient start by Andrew to this one! Really enjoyed it. I missed his step 3. so made life much harder for myself. However, did find an alternate, cool way to crack this one. Very wellbebackish. It's actually available from the start so I got focussed on the wrong area to make quick progress. Finally, many thanks to HATMAN for posting another Assassin so quickly after doing A274. More please! Thanks to Andrew for some corrections and suggestions.

Alternate way from end Andrew's step 12.
4 more steps:
paste candidates into A277 in SudokuSolver or download attached file and open with SudokuSolver:
.-------------------------------.-------------------------------.-------------------------------.
| 13 26 26 | 57 57 9 | 4 8 13 |
| 14 58 478 | 148 23 23 | 6 59 79 |
| 3457 4789 345789 | 1468 468 468 | 13 57 2 |
:-------------------------------+-------------------------------+-------------------------------:
| 234567 4678 2345678 | 234569 1234569 78 | 235 1379 46789 |
| 234567 1235 123456789 | 234569 24569 123456 | 235 1379 46789 |
| 89 1235 123456789 | 78 1234569 123456 | 1235 46 46789 |
:-------------------------------+-------------------------------+-------------------------------:
| 89 1235 25 | 23456789 123456789 12345678 | 13789 12346 134567 |
| 234567 469 479 | 2345678 1234567 12345678 | 13789 12346 134567 |
| 2456 46789 123456789 | 23456789 56789 45678 | 13789 12346 4567 |
'-------------------------------.-------------------------------.-------------------------------'

13. r8c6 sees all of n9 apart from r7c789 -> must repeat there.
13a. "45" on n9: 1 outie r8c6 + 11 = 3 innies r7c789
13b. since r8c6 repeats in r7c789 -> the other two innies must make up the Innie Outie Difference (IOD) of 11
13c. -> 13(2)r9c56 which sees r8c6 (and therefore one of r7c789), cannot both repeat in n9 in r7c789 since the IOD is 11
13d. -> the two 13(2) cages at r8c23 and r9c56 cannot have the same two digits in them
13e. -> at least one of those two 13(2) cage must have {49/58}(can't both be {67}) = [4/5]
13f. -> {45} blocked from 9(2)n8 since it sees both 13(2)n8 and h13(2)r8c23
13g. 9(2) = [81]{/27/36}(no 4,5)

14. 21(5)r8c1: only combination without 1 is {23457}: but it must have one of 2,3,5 in r9c4 to avoid clash with r7c23: but that leaves {47} in n7 which clashes with r8c23
14a. 21(5) must have 1 -> caged x-wing on 1 which must be in 34(7)r8c6: no other 1 in r89 [edit: Andrew correctly noticed that there is only one 1 in the 21(5) at r9c3 so it should be placed at this point rather than doing a caged x-wing; then 1 in 34(7)r8c6 locked for r8]
14b. 9(2)r8c4 = {27/36} = [6/7..]

15. {67} blocked from 13(2)r8c23 by 9(2)r8c4 -> 13(2) = {49}: both locked for r8 and n7
15a. -> 13(2)r9c56 = {58} only ({67} blocked by 9(2)n8 & must have a different combo to 13(2)r8c23); both locked for r9 and n8
15b. r67c1 = [98]

16. 8 in c2 only in r234c2; r3c3 sees all those -> no 8 in r3c3 (Common Peer Elimination CPE)
16a. Hidden single 8 in D\ -> r2c2 = 8

Cracked.
Cheerio
Ed


Attachments:
A277 Andrew WT end step 12.ssv [80.75 KiB]
Downloaded 600 times
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