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 Post subject: Ix Killer 1
PostPosted: Sun Mar 29, 2015 8:03 pm 
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Joined: Sat Mar 28, 2015 8:36 pm
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Hello, I have decided to try my hand at creating killer sudoku, and after a few practice attempts, I think I have created one of relatively good quality.

Image
SS Score: 1.15

Code: paste into solver:
3x3::k:6671:6671:6671:1819:1306:1306:4627:3093:3093:6671:4877:4877:1819:4622:4622:4622:4627:3093:6671:4877:4877:3356:3356:4369:4369:4369:4627:1815:1815:3352:2310:3340:3340:3340:5386:5386:4377:3088:3352:3595:2310:4103:4103:2052:5386:4377:3088:1810:3595:5384:3329:4103:2052:4357:3092:3088:1810:3595:5384:5384:3329:2052:4357:5654:3092:1810:3337:3075:3075:3075:3072:4357:5654:5654:3092:3337:3337:2818:2818:2818:3072:

Solution:
1 7 9 6 3 2 8 4 5
4 2 8 1 7 5 6 9 3
5 6 3 9 4 8 2 7 1
2 5 7 4 1 3 9 6 8
8 3 6 2 5 9 4 1 7
9 1 4 7 8 6 3 5 2
3 8 1 5 9 4 7 2 6
7 4 2 3 6 1 5 8 9
6 9 5 8 2 7 1 3 4

Any sort of feedback is appreciated.

(Moderator Note). This puzzle was originally posted as A first attempt. It will be included in archive part L as Ix Killer 1 (A first attempt).


Last edited by ixsetf on Mon Apr 06, 2015 4:23 am, edited 2 times in total.

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 Post subject: Re: A first attempt.
PostPosted: Mon Mar 30, 2015 4:44 am 
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1893
Location: Lethbridge, Alberta, Canada
Welcome ixsetf! It's great to have a new puzzle creator on the forum! :D

This killer isn't particularly difficult, with an easy start, but it's good enough to post on this forum.

May I suggest that next time you post a killer in this forum, you include the solution either in a hidden window or as tiny text.

I try to write walkthroughs for all puzzles posted on the forum.

Here is my walkthrough for A First Attempt:
Prelims

a) R12C4 = {16/25/34}, no 7,8,9
b) R1C56 = {14/23}
c) R3C45 = {49/58/67}, no 1,2,3
d) R4C12 = {16/25/34}, no 7,8,9
e) R45C3 = {49/58/67}, no 1,2,3
f) 9(2) cage at R4C4 = {18/27/36/45}, no 9
g) R56C1 = {89}
h) 13(2) cage at R6C6 = {49/58/67}, no 1,2,3
i) 12(2) cage at R8C8 = {39/48/57}, no 1,2,6
j) 21(3) cage at R4C8 = {489/579/678}, no 1,2,3
k) 8(3) cage at R5C8 = {125/134}
l) 7(3) cage at R6C3 = {124}
m) 21(3) cage at R6C5 = {489/579/678}, no 1,2,3
n) 22(3) cage at R8C1 = {589/679}
o) 11(3) cage at R9C6 = {128/137/146/236/245}, no 9

Steps resulting from Prelims
1a. Naked pair {89} in R56C1, locked for C1 and N4, clean-up: no 4,5 in R45C3
1b. Naked pair {67} in R45C3, locked for C3 and N4, clean-up: no 1 in R4C12
1c. 22(3) cage at R8C1 contains 9 -> R9C2 = 9, R89C1 = 13 = {67}, locked for C1 and N7, clean-up: no 3 in R8C8
1d. Naked triple {124} in R6C3, locked for C3
1e. 8(3) cage at R5C8 = {125/134}, 1 locked for C8

2. 45 rule on N7 3 innies R7C23 + R8C3 = 11 = {128/245} -> R7C2 = {58}, 2 locked for C3 and N7

3. 12(3) cage at R5C2 = {138/345}, no 2, 3 locked for C2
3a. 2 in N4 only in R4C12 = {25}, locked for R4 and N4, clean-up: no 4,7 in R5C5

4. R12C4 = {16/25} (cannot be {34} which clashes with R1C56)
4a. Killer pair 1,2 in R12C4 and R1C56, locked for N2

5. Max R123C1 = 12 -> min R1C23 = 14, no 1,2,3,4 in R1C23, max R1C2 = 8 -> no 5 in R1C3
[This step would be clearer written as
26(5) cage at R1C1 requires at least two of 6,7,8,9 (because {23459} only totals 23) -> no 1,2,3,4,5 in R1C23]
5a. Hidden killer pair 6,7 in R1C2 and R23C2 for C2, R23C2 cannot be {67} (because min R23C3 = 8) -> R1C2 = {67}, R23C2 contains one of 6,7
5b. Max R1C23 = 16 -> min R123C1 = 10 must contain 5, locked for C1 and N1 -> R4C12 = [25]
5c. R7C2 = 8 -> R56C2 = 4 = {13}, locked for C2 and N4 -> R6C3 = 4, clean-up: no 5 in R6C6, no 9 in R7C7
5d. Naked pair {12} in R78C3, locked for N7 -> R8C2 = 4, R7C1 = 3, R9C3 = 5, clean-up: no 7 in R8C8, no 8 in R9C9
5e. R123C1 = {145} = 10 -> R1C23 = 16 -> R1C2 = 7, R1C3 = 9

6. 45 rule on C4 3 outies R359C5 = 11 = {128/137/146/236/245}, no 9, clean-up: no 4 in R3C4
6a. 7,8 of {128} must be in R3C5 -> no 7,8 in R59C5, clean-up: no 1 in R4C4

7. 45 rule on R89 2 remaining innies R8C39 = 11 -> R8C3 = 2, R8C9 = 9, R7C3 = 1, clean-up: no 3 in R9C9
7a. 8(3) cage at R5C8 = {125/134}, 1 locked for N6
7b. 1 in N9 only in R89C7, locked for C7
7c. R8C9 = 9 -> R67C9 = 8 = [26/35/62], no 4,7,8, no 5 in R6C9

8. 12(3) cage at R8C5 = {138/156}, no 7, 1 locked for R8
8a. Killer pair 5,8 in 12(3) cage and R8C8, locked for R8

9. 45 rule on R4 3 outies R5C359 = 18 = {378/567} (cannot be {468} because 4,8 only in R5C9), no 1,2,4, 7 locked for R5, clean-up: no 7,8 in R4C4
9a. R359C5 (step 6) = {137/146/236/245} (cannot be {128} because 1,2 only in R9C5), no 8, clean-up: no 5 in R3C4
9b. 1,2 only in R9C5 -> R9C5 = {12}
9c. 4 of {245} only in R3C5 -> no 5 in R3C5, clean-up: no 8 in R3C4

10. 45 rule on N2 3 innies R2C56 + R3C6 = 20 = {389/578} (cannot be {479/569} which clash with R3C45), no 4,6
10a. 45 rule on N2 1 innie R3C6 = 1 outie R2C7 + 2, no 2,4,8,9 in R2C7, no 3 in R3C6
10b. 18(3) cage at R2C5 = {369/567} (cannot be {378} which clashes with R2C3) -> R2C7 = 6, R3C6 = 8, R23C2 = [26], R23C3 = [83], clean-up: no 1,5 in R1C4, no 7 in R3C45
10c. R3C45 = [94]
10d. 18(3) cage = {567} (only remaining combination), locked for R2, R2C4 = 1 -> R1C4 = 6, R2C1 = 4, R2C9 = 3, R2C8 = 9, clean-up: no 3 in R5C5, no 5 in R7C9 (step 7c)
10e. R3C6 = 8 -> R3C78 = 9 = {27}, locked for N3

11. 1 in R4 only in R4C56, locked for N5
11a. 13(3) cage at R4C5 = {139/148}, no 6,7

12. 13(3) cage at R8C4 = {238/247} (cannot be {148} because 4,8 only in R9C4, cannot be {346} because R9C5 only contains 1,2) -> R9C5 = 2, R89C4 = [38/74], R1C56 = [32]
12a. 2,5 in C4 only in 14(3) cage at R5C4 = {257}, locked for C4 -> R8C4 = 3, R9C4 = 8, R4C4 = 4, R5C5 = 5, 14(3) cage = [275], R2C56 = [75]

13. Naked triple {678} in R4C389, locked for R4, 8 also locked for N6
13a. 21(3) cage at R4C8 = {678} (only remaining combination), locked for N6 -> R67C9 = [26], R45C9 = [87], R4C8 = 6

14. R9C9 = 4, R7C8 = 2 -> R56C8 = 6 = [15], R8C8 = 8, R1C8 = 4, R1C9 = 5 (cage sum)

and the rest is naked singles.

Solution:
1 7 9 6 3 2 8 4 5
4 2 8 1 7 5 6 9 3
5 6 3 9 4 8 2 7 1
2 5 7 4 1 3 9 6 8
8 3 6 2 5 9 4 1 7
9 1 4 7 8 6 3 5 2
3 8 1 5 9 4 7 2 6
7 4 2 3 6 1 5 8 9
6 9 5 8 2 7 1 3 4

Rating Comment:
I'll rate my walkthrough for A First Attempt at Easy 1.0. I used a hidden killer pair.


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 Post subject: Re: A first attempt.
PostPosted: Mon Mar 30, 2015 5:48 am 
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Thanks for the feedback! I edited the solution into my post and will add it to posts in the future. Also glad to hear the puzzle was on the easy side, as I'm sure thats not something you would say for any of my other attempts. :lol:


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 Post subject: Re: A first attempt.
PostPosted: Sun Apr 05, 2015 6:08 pm 
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Joined: Tue Jun 16, 2009 9:31 pm
Posts: 280
Location: California, out of London
Thanks ixsetf. I'll agree with Andrew this was not too difficult. I thought it was a nice cage design. Here's how I did it.

Hidden Text:
1. 17(2)c1 = {89}
-> 13(2)n4 = {67}
Also 22(3)n7 = [{67}9]
-> (67) in n1 in r123c2

2. 7(3)c3 = {124}
-> Min r23c3 = +8
-> Max r23c2 = +11
-> r23c2 cannot be {67}
-> r1c2 from (67)
-> Max r1c23 = +16
-> Min r123c1 = +10
-> Innies c1 -> Max r47c1 = +5 (no 5)
-> 5 in c1 in r123c1
-> 5 in n4 in r456c2
-> HS 5 in c3n7 -> r9c3 = 5
-> 12(3)n7 = [{34}5]
-> 7(3)c3 = [4{12}]
-> r7c2 = 8
-> r56c2 = {13}
-> 7(2)n4 = [25]
Also 12(3)n7 = [345]
-> r123c1 = {145}
-> r1c23 = [79]
-> r23c2 = {26}
-> r23c3 = {38}

3. Given r7c1 = 3 -> Innies r89 r8c39 = +11 = [29]
-> r7c3 = 1
-> 1 in 8(3)c8 in r56c8
-> 1 in r4 in r4c456

4. Outies c4 -> r359c5 = +11
Since r3c5 is min 4 -> r59c5 is max +7 -> no (789) in r59c5
-> Min r4c4 = 3
-> 1 in r4 in r4c56

5. Given r9c3 = 5 -> Outies r9 = r8c148 = +18.
Previous placements -> 12(2)n9 only from [84] or [57]
Also we know r89c1 is {67} and (249) already placed in r8
-> a) if 12(2)n9 = [84] -> r8c14 = [73]
-> b) if 12(2)n9 = [57] -> r89c1 = [76] -> r8c4 = 6.
->Either way r89c1 = [76]
Also 13(3)n8 only from [382] or [6{34}]
-> 1 in n8 in r8c56 or r9c6

6. -> 1 in n2 in c4 -> 7(2)n2 = {16}
-> 5(2)n2 = {23}
Also -> 13(3)n8 = [382]
-> Innies c4 r34c4 = +13 = [94]
-> r3c5 = 4 and r5c5 = 5
-> 14(3)c4 = [{27}5]
-> 21(3)n58 = [894] (Since it can't have a 5 and 8 already in r7 and 9 in r7 in r7c56)
-> 13(2)n59 = [67]

7. {38} in r23c3 prevents 18(3)r2 = {378}
-> 18(3)r2 = [756]
-> r3c6 = 8
-> 19(4)n1 = [2863]
-> 17(3)r3 = [827]
etc.


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