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 Post subject: Assassin 442
PostPosted: Sat Sep 16, 2023 3:17 am 
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Grand Master
Grand Master

Joined: Wed Apr 16, 2008 1:16 am
Posts: 1044
Location: Sydney, Australia
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Assassin 442
Cage pattern started out as one of grostons that he showed us (18 June Hard). Felt like could always make some progress. Fun one though still hard. It gets 1.70. JSudoku has an easier time than many recent.
triple click code:
3x3::k:4864:4864:4864:3585:3585:7426:7426:7426:7426:4864:2563:2563:772:772:11013:4614:4614:7426:5639:5639:4104:4104:4104:11013:4614:4614:1033:5639:2826:4363:4363:11013:11013:11013:11013:1033:5639:2826:4363:8204:11013:11013:3853:4366:2831:3088:3088:8204:8204:8204:7702:3853:4366:2831:3088:8466:8204:8204:7702:7702:3853:1299:5140:8466:8466:8466:7702:1557:1557:4625:1299:5140:8466:8466:7702:7702:4625:4625:4625:5140:5140:
solution:
+-------+-------+-------+
| 1 6 4 | 5 9 3 | 7 2 8 |
| 8 3 7 | 1 2 4 | 6 5 9 |
| 5 9 2 | 6 8 7 | 4 3 1 |
+-------+-------+-------+
| 2 4 9 | 7 5 8 | 1 6 3 |
| 6 7 1 | 2 3 9 | 5 8 4 |
| 3 5 8 | 4 6 1 | 2 9 7 |
+-------+-------+-------+
| 4 2 3 | 9 7 6 | 8 1 5 |
| 7 8 6 | 3 1 5 | 9 4 2 |
| 9 1 5 | 8 4 2 | 3 7 6 |
+-------+-------+-------+
Cheers
Ed


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 Post subject: Re: Assassin 442
PostPosted: Mon Sep 18, 2023 10:47 pm 
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Grand Master
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1895
Location: Lethbridge, Alberta, Canada
Thanks Ed for making that puzzle into an enjoyable Assassin! I particularly liked the way when I was working with combinations for the 6-cell cages (no difficult combination analysis) that it sometimes gave me unexpected progress elsewhere, without trying for that result. And, very unusual for me, no forcing chains.

Here's how I solved Assassin 442:
Prelims

a) R1C45 = {59/68}
b) R2C23 = {19/28/37/46}, no 5
c) R2C45 = {12}
d) R34C9 = {13}
e) R45C2 = {29/38/47/56}, no 1
f) R56C8 = {89}
g) R56C9 = {29/38/47/56}, no 1
h) R78C8 = {14/23}
i) R8C56 = {15/24}
j) 43(8) cage at R2C6 = {13456789}, no 2

1a. Naked pair {12} in R2C45, locked for R2 and N2, no 8,9 in R2C23
1b. Naked pair {13} in R34C9, locked for C9, no 8 in R56C9
1c. Naked pair {89} in R56C8, locked for C8 and N6, clean-up: no 2 in R56C9
1d. 2 in N6 only in R56C7, locked for C7
1e. 15(3) cage at R5C7 contains 2 = {249/258/267), no 1,3
1f. 8,9 on {249/258} only in R7C7 -> no 4,5 in R7C7
1g. 45 rule on N3 2(1+1) outies R1C6 + R4C9 = 6 = [33/51]
1h. 45 rule on R12 2 outies R2C19 = 17 = {89}, locked for R2
1i. 19(4) cage at R1C1 cannot contain both on 8,9 -> no 8,9 in R1C123
1j. Hidden killer pair 8,9 in R1C45 and R1C789 for R1, R1C45 contains one of 4,5 -> R1C789 must contain one of 8,9 -> 29(5) cage at R1C6 must contain both of 8,9 in R1C789 + R2C9, locked for N3
1k. 29(5) cage = {23789/34589} (cannot be {14789/24689} because R1C6 only contains 3,5, cannot be {15689} which clashes with R1C45), no 1,6, 3 locked for R1
1l. 6 in N3 only in 18(4) cage at R2C7 = {1467/2367/3456}
1m. Killer pair 1,3 in 18(4) cage and R3C9, locked for N3
1n. R1C6 = 3 (hidden single in R1) -> R4C9 = 3, R3C9 = 1, clean-up: no 8 in R5C2
1o. Min R3C45 = 9 -> max R3C3 = 7
1p. 43(8) cage at R2C6 = {13456789} -> R5C5 = 3, clean-up: no 8 in R4C2
1q. 1 in R1 only in R1C123 -> 19(4) cage at R1C1 = {1279/1459/1468} (cannot be {1567} which clashes with R2C23 and doesn’t contain one of 8,9)
1r. Killer pair 4,7 in 19(3) cage and R2C23, locked for N1
1s. 8,9 in N1 only in R2C1 + R3C12, CPE no 8,9 in R45C1
1t. 45 rule on N9 3 innies R789C7 = 20 = {389/479/569/578}, no 1
1u. R4C7 = 1 (hidden single in C7)

2a. 45 rule on N9 1 innie R7C7 = 2 outies R9C56 + 2
2b. Max R9C56 = 7, no 7,8,9 in R9C56
2c. R9C56 cannot total 4 -> no 6 in R7C7
2d. R9C56 cannot total 5 = {14} which clashes with R8C56 -> no 7 in R7C7
2e. 15(3) cage at R5C7 (step 1e) = {249/258) (cannot be {267} because R7C7 only contains 8,9), no 6,7
2f. Killer pair 4,5 in R56C7 and R56C9, locked for N6
2g. R789C7 (step 1t) = {389/569} (cannot be {479} = 9{47} which clashes with 15(3) cage = {24}9, cannot be {578} = 8{57} which clashes with 15(3) cage = {25}8)
2h. R789C7 = {389} (only remaining combination, cannot be {569} = 9{56} because then R9C56 cannot total 7), locked for C7 and N9, clean-up: no 2 in R78C8
2i. Naked pair {14} in R78C8, locked for N9, 4 locked for C8
2j. R12C9 = {89} (hidden pair in C9)
2k. 4 in C9 only in R56C9 = {47}, locked for N6, 7 locked for C9 -> R4C8 = 6, R9C8 = 7 (hidden single in N9), clean-up: no 5 in R5C2
2l. Naked pair {25} in R56C7, 5 locked for C7, R7C7 = 8 (cage sum)
2m. R89C7 = {39} = 12 -> R9C56 = 6 = {15/24}, no 6
2n. Naked quad {1245} in R89C56, locked for N8
2o. 43(8) cage at R2C6 = {13456789}, CPE no 4,5,7,8,9 in R6C6

3a. 8 in N8 only in R89C4, locked for C4, clean-up: no 6 in R1C5
3b. 30(6) cage at R6C6 must contain 8 = {123789/135678/234678} (cannot be {124689} because 1,2,4 only in R6C6 + R9C3, cannot be {134589} because 4,5 only in R9C3)
3c. 1,2,4,5 only in R6C6 + R9C3 -> R6C6 = {12}, R9C3 = {1245}
3d. R7C6 = 6 (hidden single in C6)
3e. 30(6) cage = {135678/234678}, no 9 -> R7C5 = 7, R9C3 = {45}, R7C4 = 9 (hidden single in N8), clean-up: no 5 in R1C5
3f. Killer pair 4,5 in R9C3 and R9C56, locked for R9
3g. Hidden killer pair 1,2 in R6C6 and R89C6 for C6, R6C6 = {12} -> R89C6 must contain one of 1,2 and must contain one of 4,5
3h. Hidden killer pair 4,5 in R2345C6 and R89C6 for C6, R89C6 contains one of 4,5 -> R2345C6 must contain one of 4,5 -> R4C5 = {45} (only remaining uncompleted cell in 43(8) cage at R2C6)
3i. R136C5 = {689} (hidden triple in C6), 9 locked for N2
3j. 45 rule on N7 3 innies R7C13 + R9C3 = 12 = {345} (only possible combination), locked for N7
3k. Min R7C1 = 3 -> max R6C12 = 9, no 9
3l. R6C8 = 9 (hidden single in R6C) -> R5C8 = 8
3m. Killer pair 1,4 in R8C56 and R8C8, locked for R8
3n. 16(3) cage at R3C3 = {259/268/349/367} (cannot be {358} which clashes with R1C45, cannot be {457} because R3C5 only contains 6,8,9)
3o. 2,3 only in R3C3 -> R3C3 = {23}
3p. 45 rule on N1 3 innies R3C123 = 16 = {259/268/358}
3q. R3C3 = {23} -> no 2,3 in R3C12
3r. R3C38 = {23} (hidden pair in R3)

4a. 3 in R6 only in R6C123, 3 in R7 only in R7C13 -> 12(3) cage at R6C1 and 32(6) cage at R5C4 must both contain 3
4b. 12(3) cage at R6C1 = {138/237/345}, no 6
4c. 6 in R6 only in R6C345, locked for 32(6) cage, no 6 in R5C4
4d. 6 in N4 only in R5C123, locked for N4
4e. 32(6) cage must contain 3,6,9 = {135689/234689/235679}, 3 locked for C3
4f. R3C3 = 2 -> R23C8 = [53], R2C2 = 3 (hidden single in R2) -> R2C3 = 7, R1C78 = [72] (hidden pair in R1), R2C6 = 4, R4C5 = 5, clean-up: no 6 in R5C2
4g. R3C3 = 2 -> R3C45 = 14 = [59/68]
4h. R3C6 = 7 (hidden single in R3) -> R45C6 = [89], R6C5 = 6, clean-up: no 2 in R4C2
4i. 17(3) cage at R4C3 = {179/269/467} -> R4C4 = {27}, R5C3 = {16}
4j. 4 in C4 only in R56C4, locked for 32(6) cage, no 4 in R67C3
4k. 32(6) cage = {234689} (only remaining combination) -> R56C4 = {24}, 2 locked for C4 and N5, R67C3 = [83], R4C4 = 7, R6C6 = 1
4l. Naked pair {49} in R4C23, 4 locked for N4 -> R4C1 = 2, R45C2 = [47], R4C3 = 9, R4C4 = 7 -> R5C3 = 1 (cage sum)
4m. R6C2 = 5, R45C1 = [26] = 8 -> R3C12 = 14 = [59]

and the rest is naked singles.


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