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 Post subject: Assassin 69 v1.5 Revisit
PostPosted: Fri Sep 02, 2022 6:32 pm 
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Grand Master
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Joined: Wed Apr 16, 2008 1:16 am
Posts: 1043
Location: Sydney, Australia
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Assassin 69 V1.5 Revisit
This might not be hard enough for us now going by Andrew's rating on the original puzzle. It gets 1.70 and JSudoku thinks its quite hard.
Andrew: Mike also rated it at 1.5 when he posted this variant of Assassin 69.
triple click code:
3x3::k:5888:5888:3074:3074:3332:2821:2821:6919:6919:5385:5888:5888:5888:3332:6919:6919:6919:3857:5385:5385:5908:5908:3332:4887:4887:3857:3857:5385:5908:5908:3614:4383:3616:4887:4887:3857:2852:2852:6438:3614:4383:3616:4650:3371:3371:2861:6438:6438:3614:4383:3616:4650:4650:5429:2861:2861:6438:1337:3898:2875:4650:5429:5429:2623:2623:4161:1337:3898:2875:4165:2630:2630:2376:2376:4161:4161:3898:4165:4165:1359:1359:
Solution:
+-------+-------+-------+
| 3 1 7 | 5 4 2 | 9 6 8 |
| 2 8 4 | 7 6 9 | 3 1 5 |
| 9 6 5 | 8 3 1 | 4 7 2 |
+-------+-------+-------+
| 4 7 3 | 9 2 5 | 6 8 1 |
| 6 5 8 | 1 7 3 | 2 9 4 |
| 1 9 2 | 4 8 6 | 5 3 7 |
+-------+-------+-------+
| 7 3 6 | 2 1 4 | 8 5 9 |
| 8 2 9 | 3 5 7 | 1 4 6 |
| 5 4 1 | 6 9 8 | 7 2 3 |
+-------+-------+-------+
Cheers
Ed


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PostPosted: Wed Sep 14, 2022 5:36 am 
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Joined: Wed Apr 23, 2008 6:04 pm
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Thanks Ed; I'm happy to try selected Revisits for a while.

At first, after an easy start, I was struggling until I realised that I wasn't looking carefully enough at my worksheet; after that it was a lot easier. As with the earlier Revisits I haven't checked how I solved it originally but I expect I used a lot of the same steps.

Thanks Ed for pointing out a flaw in part of my step 2b; some of my solving path reworked.
Here's how I solved Assassin 69 V1.5 Revisited:
Prelims

a) R1C34 = {39/48/57}, 1,2,6
b) R1C67 = {29/38/47/56}, no 1
c) R5C12 = {29/38/47/56}, no 1
d) R5C89 = {49/58/67}, no 1,2,3
e) R78C4 = {14/23}
f) R78C6 = {29/38/47/56}, no 1
g) R8C12 = {19/28/37/46}, no 5
h) R8C89 = {19/28/37/46}, no 5
i) R9C12 = {18/27/36/45}, no 9
j) R9C89 = {14/23}
k) 11(3) cage at R6C1 = {128/137/146/236/245}, no 9
l) 21(3) cage at R6C9 = {489/579/678}, no 1,2,3

1a. 45 rule on R89 3 outies R7C456 = 7 = {124}, locked for R7 and N8
1b. R8C4 = 3 -> R7C456 = [214], R8C6 = 7, clean-up: no 9 in R1C3, no 4,7 in R1C7
1c. 14(3) cage at R4C4 = {149/158/167}, 1 locked for R4 and N5
1d. 11(3) cage at R6C1 = {137/236} (cannot be {128/146/245} because 1,2,4 only in R6C1), no 5,8, 3 locked for R7 and N7, clean-up: no 6 in R9C12
1e. 1,2 only in R6C1 -> R6C1 = {12}
1f. 15(3) cage at R7C5 = 1{59/68}
1g. 13(3) cage at R1C5 = {238/247/346} (cannot be {256} which clashes with 15(3) cage), no 5,9
1h. 17(3) cage at R4C5 = {278/359/368/467} (cannot be {269/458} which clash with 15(3) cage)
1i. 45 rule on N8 2 innies R9C46 = 14 = {59/68}

2a. Combined cage R89C89 = {19}{23}/{28}{14}/{46}{23}, 2 locked for N9
2b. 16(4) cage at R8C7 = {169/178/358/457} (cannot be {349} which clashes with R9C89, cannot be {367} because 3,7 only in R9C7)
2c. {169} must have 6 in R9C6 (R89C7 cannot be {16} which clashes with combined cage) -> no 6 in R89C7, no 9 in R9C6, clean-up: no 5 in R9C4 (step 1i)
[Ed pointed out that I can’t completely eliminate {169} at this stage, I’d been looking at the text of step 2a not the diagram; so partly reworked until that can be eliminated.]
2d. Consider combinations for R7C12 = {36/37}
R7C12 = {36} => 6 in N9 only in R8C89 = {46}, 4 locked for N9 => R9C89 = {23}, 3 locked for N9
or R7C12 = {37} => R9C7 = 7 (hidden single in N9)
-> 16(3) cage at R8C7 = {169/178/457}, no 3
2e. 7 of {178/457} must be in R9C7 -> no 4,5,8 in R9C7
2f. 3 in N9 only in R9C89 = {23}, 2 locked for R7 and N9, clean-up: no 8 in R8C89, no 7 in R9C12
2g. 4 in N9 only in R8C789, locked for R8, clean-up: no 6 in R8C12
2h. Killer pair 5,8 in R9C12 and R9C46, locked for R9, clean-up: no 6,9 in R8C5 (step 1f)
2i. 16(3) cage at R8C3 = {169/178} (cannot be {259 because 2,5 only in R8C3, cannot be{457} because no 4,5,7 in R9C4, cannot be {268} = [268] because R89C5 = [59] clashes with R9C6 = 5 or alternatively R9C34 = [68] clashes with R9C46 = [86], CCC), no 2,4,5
2j. 2 in N7 only in R8C12 = {28}, 8 locked for R8 and N9 -> R8C5 = 5, R9C5 = 9 (cage sum), clean-up: no 1 in R9C12
2k. Naked pair {68} in R9C46, 6 locked for R9
2l. 16(3) cage at R8C7 = {169/178}, no 4, 1 locked for C7 and N9, clean-up: no 9 in R8C89
2m. Naked pair {46} in R8C89, 6 locked for R8 and N9
2n. Naked pair {45} in R9C12, 5 locked for N7
2o. 1,9 in N7 only in R789C3, locked for C3
2p. 25(4) cage at R5C3 = {2689/3589/3679/4579/4678} (cannot be R567C3 = {1789} because {789} clashes with R89C3), no 1
2q. 14(3) cage at R4C6 = {239/356}, no 8, 3 locked for C6 and N5, clean-up: no 8 in R1C7
2r. 17(3) cage at R4C5 (step 1h) = {278/467}, 7 locked for C5 and N5

3a. R5C4 = 1 (hidden single in R5)
3b. 14(3) cage at R4C4 (step 1c) = {149/158}, no 6
3c. 45 rule on R1234 3 innies R4C456 = 16 = {259/268/349/358/457} (cannot be {367} because no 3,6,7 in R4C4)
3d. R4C456 = {259/268/457} (cannot be {349/358} because 13(2) in R4C45 + R4C6 = 3 clashes with the same 1 + 13(2) in 14(3) cage at R4C4, CCC), no 3 in R4C6
3e. 8 of {268} must be in R4C4, 7 of {457} must be in R4C5 -> no 4,8 in R4C5

4c. R9C46 = {68}
4b. 45 rule on C789 4 outies R1239C6 = 20 contains 1,8 = {1289/1568}
4c. 45 rule on C123 4 outies R1239C4 = 26 contains 7 = {4679/5678}
4d. R123C9 cannot be {567}8 which clashes with R1239C6 = {158}6 -> R9C46 = [68] -> R89C3 = 10 = [91], R89C7 = [17], clean-up: no 3 in R1C7

[Back to some of my original steps, renumbered and in some cases simplified.]
5a. 21(3) cage at R6C9 = {489/579} (cannot be {678} because 6,7 only in R7C89), no 6
5b. 4,7 only in R6C9 -> R6C9 = {47}
5c. 21(3) cage = {489/679}, 9 locked for N9
5d. Combined half cage R5C89 + R6C9 = {58}4/{67}4/{49}7/{58}7
5e. 45 rule on N69 3 remaining innies R4C789 = 15 = {159/168} (cannot be {456} which clashes with R5C89, cannot be {249/258/267} which clash with R4C456, step 3d, cannot be {348/357} which clash with R5C89 + R6C9), no 2,3,4,7, 1 locked for R4 and N6
5f. R6C1 = 1 (hidden single in N4) -> R7C12 = {37}, R7C3 = 6 (hidden single in R7)
5g. 45 rule on N47 3 remaining innies R4C123 = 14 contains 3 (hidden single in R4) = {239/347} (cannot be {356} which clashes with R4C789), no 5,6,8
5h. 6 in N4 only in R5C12 = {56}, locked for R5, 5 locked for N4, clean-up: no 7,8 in R5C89
5i. Naked pair {49} in R5C89, locked for R5 and N6 -> R6C9 = 7 -> R7C89 = {59}, R7C7 = 8 (hidden single in R7), clean-up: no 5 in R4C789
5j. R4C7 = 6, clean-up: no 5 in R1C6
5k. Naked pair {23} in R5C67, locked for R5
5l. 17(3) cage at R4C5 = {278} (only remaining combination), 2,8 locked for C5 and N5
5m. R5C6 = 3 -> R46C6 = 11 = [56], clean-up: no 5 in R1C7
5n. R5C7 = 2 -> R1C67 = [29], clean-up: no 3 in R1C3
5o. 4 in C7 only in R23C7, locked for N3
5p. 5 in C3 only in R123C3, locked for N1

6a. 15(4) cage at R2C9 = {1257/1356}, no 8 -> R4C9 = 1
6b. 15(4) cage = {1257/1356}, 5 locked for N3
6c. R4C78 = [68] = 14 -> R3C67 = 5 = [14]
6d. R2C67 = [93] -> R6C78 = [53], R9C89 = [23]
6e. 15(4) cage = {1257} -> R3C8 = 7, R23C9 = {25}, 5 locked for C9
6f. Naked pair {16} in R12C8, 6 locked for C8 and N3 -> R1C9 = 8, clean-up: no 4 in R1C34
6g. Naked pair {57} in R1C34, 7 locked for R1

7a. 23(4) cage at R3C3 = {2579/3578} (cannot be {3479} because R3C4 only contains 5,8, cannot be {2489} = [2894] which clashes with R4C4), no 4
7b. R4C123 (step 5g) = {239/347}
7c. 23(4) cage = {3578} (cannot be {2579} = [2597] because R4C123 cannot contain both of 7,9), no 2,9
7d. Naked pair {37} in R4C23, locked for R4 and N4, 3 locked for 23(4) cage
7e. R57C3 = [86] = 14 -> R6C23 = 11 = [92]
7f. R3C34 = [58], R1C34 = [75]
7g. R3C1 = 9 (hidden single in R3), R4C1 = 4 -> R2C1 + R3C2 = 8 = {26}

and the rest is naked singles.


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