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 Post subject: Messy One #8
PostPosted: Wed Jun 28, 2023 9:09 am 
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Location: Sydney, Australia
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Messy One #8

This popped out when I was looking for a new Assassin. Too much of a one-trick pony for an A. Gets a score of 1.05 so perfect as a contender for best Messy One ever!! The Messy One series started here. I might have the wrong number for this new puzzle after a quick look through the archive so might need to be corrected. [edit: corrected found a #7 here with #13 [sic] shortly after
edit 2: this #8 has some symmetry to it so it may not meet the technical definition of messy. Sorry about that]


triple click code:
3x3::k:4608:4608:4608:4097:4097:4097:4097:11522:11522:4355:1796:1796:4097:4101:4101:11522:11522:2822:4355:775:775:4872:4872:10249:11522:2822:2822:3082:3082:3595:4872:10249:10249:11522:11522:11522:3082:11532:3595:4872:10249:6157:2574:11522:5135:11532:11532:11532:10249:10249:6157:2574:5135:5135:2576:2576:11532:10249:6157:6157:3089:3089:2322:2576:11532:11532:2835:2835:5652:3605:3605:2322:11532:11532:5652:5652:5652:5652:2582:2582:2582:
solution:
+-------+-------+-------+
| 7 6 5 | 1 3 2 | 4 8 9 |
| 8 3 4 | 6 7 9 | 5 1 2 |
| 9 1 2 | 5 4 8 | 7 3 6 |
+-------+-------+-------+
| 1 7 8 | 2 9 5 | 6 4 3 |
| 4 5 6 | 8 1 3 | 9 2 7 |
| 2 9 3 | 4 6 7 | 1 5 8 |
+-------+-------+-------+
| 5 2 1 | 7 8 6 | 3 9 4 |
| 3 4 7 | 9 2 1 | 8 6 5 |
| 6 8 9 | 3 5 4 | 2 7 1 |
+-------+-------+-------+
Cheers
Ed


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 Post subject: Re: Messy One #8
PostPosted: Fri Jun 30, 2023 3:47 am 
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1895
Location: Lethbridge, Alberta, Canada
Thanks Ed for a fun puzzle. Definitely a one-trick pony; after fairly routine simplifications I used one short forcing chain to crack it.

Here's how I solved Messy One #8:
Prelims

a) R23C1 = {89}
b) R2C23 = {16/25/34}, no 7,8,9
c) R2C56 = {79}
d) R3C23 = {12}
e) R45C3 = {59/68}
f) R56C7 = {19/28/37/46}, no 5
g) R7C78 = {39/48/57}, no 1,2,6
h) R78C9 = {18/27/36/45}, no 9
i) R8C45 = {29/38/47/56}, no 1
j) R8C78 = {59/68}
k) 11(3) cage at R2C9 = {128/137/146/236/245}, no 9
l) 20(3) cage at R5C9 = {389/479/569/578}, no 1,2
m) 10(3) cage at R7C1 = {127/136/145/235}, no 8,9
n) 10(3) cage at R9C7 = {127/136/145/235}, no 8,9
o) 16(5) cage at R1C4 = {12346}
p) 45(9) cages = {123456789}

1a. Naked pair {79} in R2C56, locked for R2 and N2 -> R23C1 = [89]
1b. Naked pair {12} in R3C23, locked for R3 and N1, clean-up: no 5,6 in R2C23
1c. Naked pair {34} in R2C23, locked for R2 and N1
1d. Naked triple {567} in 18(3) cage at R1C1, locked for R1
1e. R8C45 = {29/38/47} (cannot be {56} which clashes with R8C78), no 5,6
1f. 45 rule on N36 1 innie R1C7 = 4, clean-up: no 6 in R56C7, no 8 in R7C8
1g. Naked triple {123} in R1C456, locked for R1 and N2 -> R2C4 = 6
1h. Naked pair {89} in R1C89, locked for 45(9) cage at R1C8, 8 locked for N3
1i. R3C456 = {458} (hidden triple in N2), 5 locked for R3
1j. 11(3) cage at R2C9 = {137/236} -> R2C9 = {12}, R3C89 = {36/37}, 3 locked for N3
1k. 5 in N2 only in R2C78, locked for 45(9) cage at R1C8
1l. 45(9) cage at R1C8 = {123456789}, 3,4 locked for N6, clean-up: no 7 in R56C7
1m. 45 rule on N47 1 innie R9C3 = 9, clean-up: no 5 in R45C3
1n. Naked pair {68} in R45C3, locked for C3 and N4
1o. 45(9) cage at R5C2 = {123456789}, 9 locked for N4
1p. 45 rule on N8 3 remaining innies R7C456 = 21 = {489/579/678}, no 1,2,3

2a. Combined cage R78C78 = {39}{68}/{57}{68}/[84]{59}, 8 locked for N9, clean-up: no 1 in R78C9
2b. 1 in N9 only in 10(3) cage at R9C7 = {127/136/145}, 1 locked for R9
2c. R8C6 = 1 (hidden single in N8)
2d. R8C6 = 1, R9C3 = 9 -> R9C456 = 12 = {246/345} (cannot be {237} which clashes with R8C45), no 7,8, 4 locked for R9 and N8, clean-up: no 7 in R8C45
2e. R9C2 = 8 (hidden single in R9)
2f. 45 rule on R9 1 remaining innie R9C1 = 6, clean-up: no 2 in R9C456
2g. Naked triple {345} in R9C456, 3,5 locked for N8, clean-up: no 8 in R8C45
2h. 10(3) cage at R9C7 = {127} (hidden triple in N9), 2,7 locked for N9, clean-up: no 5 in R7C78
2i. Naked pair {29} in R8C45, locked for R8, 9 locked for N8, clean-up: no 5 in R8C78
2j. Naked pair {68} in R8C78, locked for N9, clean-up: no 4 in R7C8, no 3 in R78C9
2k. Naked pair {39} in R7C78, 3 locked for R7
2l. Naked pair {45} in R78C9, locked for C9
2m. Naked triple {678} in R7C456, 7 locked for R7, 6 locked for 24(4) cage at R5C6, no 6 in R56C6
2n. R6C8 = 5 (hidden single in N6)
2o. R1C2 = 6 (hidden single in R1)
2p. R2C7 = 5 (hidden single in R2)
2q. Naked pair {12} in R2C89, CPE no 1,2 in R4C9
2r. R29C9 = {12} (hidden pair in C9)

3a. 24(4) cage at R5C6 contains 6 in R7C56 = {3678}, 3 locked for C6 and N5 -> R1C6 = 2
3b. 40(7) cage at R3C6 = {1456789} (only remaining combination), no 2, 1 locked for N5
3c. 19(4) cage at R3C4 = {2458} (only remaining combination), 2 locked for C4 -> R8C45 = [92]
3d. 7 in C4 only in R67C4, locked for 40(7) cage

4a. Consider placement for 6 in 45(9) cage at R1C8
R3C7 = 6 => R8C7 = 8 => R56C7 = {19}
or 6 in R4C456 + R5C5, locked for N6 => R56C9 = 15 = {78}, locked for N6 => R56C7 = {19}
-> R56C7 = {19}, locked for C7 and N6, R7C78 = [39], R1C89 = [89], R8C78 = [86], clean-up: no 6 in R56C9
[Cracked]
4b. Naked pair {78} in R56C9, 7 locked for C9 and N6
4c. 45(9) cage at R1C8 = {123456789} -> R2C8 = 1, R3C7 = 7, R2C9 = 2, R3C89 = [36], R49C7 = [62], R45C3 = [86], R4C9 = 3
4d. R6C5 = 6 (hidden single in N5) -> R7C6 = 6 (hidden single in N6)
4e. Naked pair {78} in R7C45, CPE no 8 in R5C5
4f. 40(7) cage at R3C6 = {1456789}, CPE no 8 in R3C4
4g. 7 in R4 only in R4C12, locked for N4
4h. 12(3) cage at R4C1 = {147/237}, no 5
4i. 3 of {237} must be in R5C1 -> no 2 in R5C1
4j. R56C2 = [59] (hidden pair in N4) -> R56C7 = [91]
4k. 1 in N4 only in 12(3) cage = {147}, 4 locked for N4
4l. Naked pair {14} in R5C15, locked for R5
4m. Naked pair {23} in R6C13, locked for 45(9) cage at R5C2, 3 locked for R6
4n. Naked pair {47} in R8C23, locked for N7, 4 locked for R8

and the rest is naked singles.


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 Post subject: Re: Messy One #8
PostPosted: Fri Jun 30, 2023 10:44 pm 
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Grand Master
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Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
Haven't ready Andrew's way in detail yet but....

These are my key steps. The main one is available very early.
MO8 key steps:
Preliminaries from SudokuSolver
Cage 3(2) n1 - cells ={12}
Cage 16(2) n2 - cells ={79}
Cage 17(2) n1 - cells ={89}
Cage 14(2) n9 - cells only uses 5689
Cage 14(2) n4 - cells only uses 5689
Cage 7(2) n1 - cells do not use 789
Cage 12(2) n9 - cells do not use 126
Cage 9(2) n9 - cells do not use 9
Cage 10(2) n6 - cells do not use 5
Cage 11(2) n8 - cells do not use 1
Cage 10(3) n9 - cells do not use 89
Cage 10(3) n7 - cells do not use 89
Cage 20(3) n6 - cells do not use 12
Cage 11(3) n3 - cells do not use 9
Cage 16(5) n23 - cells ={12346}

1. 16(2)n2 = {79}: both locked for n2 and r2
1a. r23c1 = [89]

2. hidden pair 8,9 in r1 -> r1c89 = {89}: both locked for 45(9) cage, 8 for n3

3. the 10(2)r5c7 sees all the 45(9)r1c8 apart from r1c89 + r2c8 so both must repeat there
3a. -> can only be {8}[2] or {9}[1]
3b. -> r2c8 = (12)
3c. however, [91] in r12c8 + r56c7 is blocked by no 9 in r789c9
3d. -> no 9 in r1c8
3e. -> r1c89 = [89]
3f. note: still don't know which of {19/28} repeats in those two places

After that its all routine stuff until near the end,
4. {45}[3] blocked from 12(3)r4c1 by r4c48 = {245} (ALS block)
4a. -> no 3 in r5c1
Cheers
Ed


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