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 Post subject: Assassin 448
PostPosted: Fri Dec 15, 2023 6:47 pm 
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Grand Master
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Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
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X-puzzle so 1-9 cannot repeat on either diagonal. A broken 17(3)r4c6

Assassin 448
A Christmas monster!! Took me forever to find a really decent way to solve this. I knew I was missing something big since it gets a score of 'only' 1.40.

triple click code:
3x3:d:k:1792:1792:7937:7937:7937:10242:10242:10242:10242:2307:2307:7937:7937:7937:7172:7172:10242:10242:4101:4101:6406:1031:1031:7172:7172:7172:10242:4101:3336:6406:5129:5129:4362:4362:7172:4362:3336:6406:6406:5129:5129:2571:2571:5388:5388:7437:6406:6406:5646:5646:5646:5646:5388:6927:7437:7437:2832:8465:3858:3858:4371:5388:6927:7437:2832:8465:8465:3858:2580:4371:6927:6927:7437:2832:8465:8465:8465:2580:4371:6927:6927:
solution:
+-------+-------+-------+
| 5 2 3 | 7 6 8 | 1 4 9 |
| 1 8 9 | 4 2 5 | 3 6 7 |
| 7 6 4 | 3 1 9 | 8 2 5 |
+-------+-------+-------+
| 3 9 6 | 2 7 4 | 5 1 8 |
| 4 5 2 | 8 3 1 | 9 7 6 |
| 8 1 7 | 5 9 6 | 2 3 4 |
+-------+-------+-------+
| 9 4 1 | 6 8 2 | 7 5 3 |
| 6 7 8 | 1 5 3 | 4 9 2 |
| 2 3 5 | 9 4 7 | 6 8 1 |
+-------+-------+-------+
Cheers
Ed


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 Post subject: Re: Assassin 448
PostPosted: Wed Dec 20, 2023 3:29 am 
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1895
Location: Lethbridge, Alberta, Canada
Thanks Ed for your Christmas Assassin! An enjoyable puzzle. Fewer Prelims than usual but still enough for an easy start, then a harder middle and an easy end.

From the comments posted by wellbeback and Ed Assassin 447 was the December monster; I've now done it and agree that it was a monster.

Thanks Ed for pointing out a careless oversight, now corrected with only detailed changes.

Here's my walkthrough for Assassin 448:
Prelims

a) R1C12 = {16/25/34}, no 7,8,9
b) R2C12 = {18/27/36/45}, no 9
c) R3C45 = {13}
d) 13(2) cage at R4C2 = {49/58/67}, no 1,2,3
e) R5C67 = {19/28/37/46}, no 5
f) R89C6 = {19/28/37/46}, no 5
g) 11(3) cage at R7C3 = {128/137/146/236/245}, no 9

1a. Naked pair {13} in R3C45, locked for R3 and N2
1b. 45 rule on N569 1 innie R4C8 = 1, clean-up: no 9 in R5C6
1c. 1 in N3 only in 40(7) cage at R1C6 = {1456789}, no 2,3
1d. R2C7 = 3 (hidden single in N3), clean-up: no no 6 in R2C12, 7 in R5C6
1e. 2 in N3 only in R3C78, locked for R3 and 28(6) cage at R2C6
1f. 28(6) cage = {123589/123679}, no 4
1g. 45 rule on N3 3 remaining outies R123C6 = 22 = {589/679}, 9 locked for C6 and N2, clean-up: no 1 in R89C6
1h. 45 rule on N23 2 remaining outies R12C3 = 12 = [39]/{48/57}, no 1,2,6
1i. 31(6) cage at R1C3 = {234589/234679} (cannot be {235678} because R12C3 can only contain 3 when it contains 9) -> R12C3 = [39], clean-up: no 4 in R1C12
1j. 45 rule on N8 2 outies R89C3 = R89C3 = 13 = {58/67}
1k. 45 rule on N78 1 outie R6C1 = 8, clean-up: no 1 in R2C2, no 5 in 13(3) cage at R4C2
1l. 45 rule on C6789 2 outies R6C45 = 1 innie R7C6 + 12
1m. Max R6C45 = 16 -> max R7C6 = 4
1n. Min R6C45 = 13, no 1,2,3 in R6C45
1o. Max R7C6 = 4 -> min R78C5 = 11, no 1 in R78C5
1p. 45 rule on C6789 3(1+2/2+1) innies R6C67 + R7C6 = 10, no 9 in R6C7
1q. 45 rule on N4 1 outie R3C3 = 1 innie R4C1 + 1, no 2,9 in R4C1
1r. 45 rule on N1 3 innies R3C123 = 17 = {458/467}, 4 locked for R3 and N1, clean-up: no 5 in R2C12
1s. 45 rule on N9 1 innie R7C8 = 1 outie R6C9 + 1, no 9 in R6C9, no 2,9 in R7C8
1t. 45 rule on C6 using R123C6 = 22, 4 innies R4567C6 = 13 = {1237/1246/1345}, no 8, clean-up: no 2 in R5C7
1u. 25(6) cage at R3C3 = {123469/123568/124567} (cannot be {123478} which clashes with 13(2) cage)
1v. 8 of {123568} only in R3C3, 6 of {123469} must be in R3C3 (because then R4C1 = 5, hidden single in N4), 4 of {124567} must be in R3C3 (because then R4C1 = 3, hidden single in N4) -> R3C3 = {468}, clean-up: no 4,6 in R4C1
1w. 9 in N7 only in 29(5) cage at R6C1 = {14789/23789/24689/34589} (cannot be {15689} which clashes with R89C3)
1x. 11(3) cage at R7C3 = {128/137/146/236} (cannot be {245} which clashes with 29(5) cage), no 5

2a. 11(3) cage at R7C3 (step 1x) = {128/137/146/236}, 25(6) cage at R3C3 (step 1u) = {123469/123568/124567}
2b. Consider combinations for R89C3 = {58/67}
R89C3 = {58}, locked for C3
or R89C3 = {67} => 11(3) cage = {128} => 4 in C3 only in R3456C3
-> 25(6) cage = {123469/124567}, no 8, clean-up: no 7 in R4C1 (step 1m)
2c. Consider combinations for 29(5) cage at R6C1 (step 1w) = {14789/23789/24689/34589}
29(5) cage = {14789/23789/24689}, 6 or 7 locked for N7 => R89C3 = {58}
or 29(5) cage = {34589} must have 4,9 in C1 ({345/359} clash with R4C1), locked for C1 => 13(2) cage at R4C2 = {67} => 25(6) cage = {123469} with 6 in R3C3 (step 1v)
-> R89C3 = {58}, locked for N7 and 33(6) cage at R7C4), 5 locked for C3
2d. 5 in N8 only in 15(3) cage at R7C5 = {159/258/357/456}, 5 locked for C5
2e. R7C6 = {1234} -> no 2,3,4 in R89C5
2f. 8 in N8 only in 15(3) cage = {258} or R89C6 = {28} (locking cages)
-> 2 in R789C6, locked for C6 and N8, clean-up: no 8 in R5C7
2g. Consider combinations for 11(3) cage = {137/146/236}
11(3) cage = {137/236}, 3 locked for N7 => R4C1 = 3 (hidden single in C1)
or 11(3) cage = {146} => 7 in C3 only in R456C3 => 25(6) cage = {124567}
-> 25(6) cage = {124567}, R3C4 = 4 (step 1v), placed for D\, R4C1 = 3 (hidden single in C1)
2h. 13(2) cage at R4C2 = {49} (hidden pair in N4)
2i. 5 in C1 only in R13C1, locked for N1, clean-up: no 2 in R1C1
2j. 2,8 in N5 only in 20(4) cage at R4C4 = {1289/2378/2468}, no 5
2k. 20(4) cage = {1289/2378/2468} -> R45C6 + R6C456 must contain 5 and two of {19}, {37} and {46}
2l. R6C45 = R7C6 + 12 (step 1l)
2m. R6C45 + R7C6 = {67}1/[592]/{69}3/{79}4 (cannot be {49}1 which clashes with R45C6 + R6C456 = {14569}, no 4 in R6C45
[Cracked, fairly straightforward from here.]
2n. 4 in R6 only in R6C789, locked for N6, clean-up: no 6 in R5C6
2o. Disjoint 17(3) cage at R4C6 = {269/278/458/467}
2p. 4 of {458} must be in R4C6 -> no 5 in R4C6
2q. 5 in N5 only in R6C46, locked for R6
2r. R5C2 = 5 (hidden single in N4)
2s. 5 in N6 only in disjoint 17(3) cage at R4C6 = {458} -> R4C6 = 4, placed for D/, R4C79 = {58}, 8 locked for R4 and N6, R4C2 = 9 -> R5C1 = 4, clean-up: no 6 in R5C7, no 6 in R78C5, no 6 in R89C6
2t. R4C6 = 4 -> R45C6 + R6C456 must also contain 6 in R6C456, locked for R6 and N5
2u. Naked pair {27} in R4C45, locked for R4 and N5 -> R4C3 = 6
2v. 20(4) cage = {2378} (only remaining combination), 3 locked for R5 and N5, R5C6 = 1 -> R5C7 = 9, clean-up: no 9 in R78C5
2w. R6C456 = {569} -> R6C7 = 2 (cage sum)
2x. Naked pair {67} in R5C89, 7 locked for R5 and N6
2y. R5C89 = {67} = 13 -> R67C8 = 8 = [35], R6C9 = 4, R8C5 = 5 (hidden single in N8), R89C3 = [85], clean-up: no 2 in R9C6

3a. Naked quad {2378} in R7C56 + R89C6, 3,7 locked for N8
3b. 17(3) cage at R7C7 = {467} (only remaining combination), locked for C7, 6,7 locked for N9
3c. R1C7 = 1 (hidden single in C7), R1C8 = 4 (hidden single in N3), clean-up: no 6 in R1C12
3d. R1C12 = [52], 5 placed for D\ -> R6C6 = 6, placed for D\, R7C7 = 7, placed for D\, R6C45 = [59], 5 placed for D/, R4C4 = 2, placed for D\, R2C2 = 8, placed for D\ -> R5C5 = 3, placed for both diagonals, clean-up: no 7 in R123C6 (step 1g)
3e. Naked pair {67}, locked for R3, 7 locked for N1
3f. R5C3 = 2, R7C3 = 1, naked pair {67} in R2C8 + R8C2, 6,7 locked for D/, R3C7 = 8, R1C9 = 9, placed for D/
3g. R2C45 = [42] (hidden pair in R2)
3h. Naked triple {169} in R789C4, 1,6 locked for C4 and N8 -> R9C5 = 4
3i. 11(3) cage at R7C3 = {137} (only remaining combination), R8C2 = 7, placed for D/
3j. R78C5 = [85] -> R7C6 = 2 (cage sum)

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


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 Post subject: Re: Assassin 448
PostPosted: Mon Dec 25, 2023 8:27 pm 
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Grand Master
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Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
Well done Andrew! 2m is very powerful. I worked in a different area to finally crack it. Did the start quite differently also.
a448 WT:
Preliminaries from SudokuSolver
Cage 4(2) n2 - cells ={13}
Cage 7(2) n1 - cells do not use 789
Cage 13(2) n4 - cells do not use 123
Cage 9(2) n1 - cells do not use 9
Cage 10(2) n56 - cells do not use 5
Cage 10(2) n8 - cells do not use 5
Cage 11(3) n7 - cells do not use 9

Note: no clean-up done unless stated
1. "45" on n78: 1 outie r6c1 = 8
1a. no 5 in 13(2)n4

2. 4(2)n2 = {13}: both locked for r3, n2

3. "45" on n569: 1 innie r4c8 = 1

4. 1 in n3 only in 40(7) = {1456789}(no 2,3)
4a. r2c7 = 3 (hsingle n3)
4b. 2 in n3 only in r3: locked for r3, 28(6)

5. "45" on n4: 3 outies r3c123 = 17
5a. "45" on r3: 4 innies r3c6789 = 24 and must have 2 for r3
5b. = {2589/2679}(no 4)
5c. -> h17(3)r3c123 must have 4 for r3
5d. = {458/467)(no 9)
5e. 4 locked for n1
5f. no 3 in 7(2)n1
5g. no 5 in 9(2)

6. r12c3 = [39] (hsingles n1)

7. "45" on r12: 1 remaining innie r2c6 = 1 outie r3c9
7a. and they must repeat in r1c12
7b. -> both = (56)
7c. -> no 5,6 in r3c678 (step 5b)

8. "45" on c12: 4 innies r5689c2 = 16
8a. -> r56c2 <> {39} since no way for r89c2 = 4
8b. -> 25(6)r3c3 cannot be {123469}
8c. -> 25(6): no 9

9. "45" on n4: 1 outie - 1 = 1 innie r4c1
9a. = [87/76/65/54/43](no 2,9 in r4c1)

10. 9 in n4 only in 13(2) = {49}: 4 locked for n4

11. 25(6)r3c3: can't have both 4,8 since they are only in r3c3
11a. = {123568/124567}
11b. has 4 or 8 -> r3c3 = (48)
11b. -> r4c1 = 3,7 (iodn4=-1)

12. 16(3)r3c1 = {358/367/457}
12a. note: can't have both [67] in r34c1

13. "45" on n8: 2 outies n89c3 = 13 = {58/67}

Took a long long time to see this step
14. hidden killer quad 1,2,6,7 in c1 since max. 3 of those in r1234c1 (step 12a)
14a. -> at least one of 1,2,6,7 in r789c1
14b. -> {128}{67} blocked from combined cage 11(3)+h13(2) both in n9
14c. -> no 8 in 11(3)
14d. -> 8 in n9 only in h13(2) = {58}: both locked c3, 5 for n7, both for 33(6)r7c4
14e. r3c3 = 4, locked for d\
14f. -> r4c1 = 3 (iodn4=-1)

15. "45" on n9: 4 outies r56c89 = 20 and must have 3 for n6
15a. = {2369/2378/3458/3467}
15b. "45" on n9: 1 outie r6c9 + 1 = 1 innie r7c8
15c. no 9 in r6c9, no 2,9 in r7c8
15d. -> 7 in r6c9 must have {346} in r5c89 + r6c8 (no eliminations yet)

16. "45" on r6: 4 remaining innies r6c2389 = 15
16a. = {1239/1257/1347/1356/2346}
16b. since 3,4 are only in r6c89 -> 7 in r6c9 can only be from {1257}
16c. but this contradicts step 15d
16d. -> no 7 in r6c9
16e. -> no 8 in r7c8 (iodn9=+1)

17. 27(6)r6c9 has 1 or is {234567}
17a. however {23456} are all blocked from r6c9 by the iodn9 = +1
17b. -> must have 1: locked for n9 and c9
17c. -> r1c7 = 1 (hsingle n3)

Cracked
Cheers
Ed


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