inferior puzzles thread

Everything about Sudoku that doesn't fit in one of the other sections

Postby gsf » Wed Mar 22, 2006 3:52 pm

I count F:naked-single and N:hidden-single as separate techniques
for each constraint propagation iteration (grid scan) F is attempted first,
if F makes no progress then N is attempted (this goes the same for the remaining methods)
when a method makes progress a new iteration starts with the first method

this means that for a given method order (mine is FNBTYWUG),
solutions will be biased to the low-order methods
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Postby JPF » Wed Mar 22, 2006 4:19 pm

Hi Vidarino , Hi Ruud

Could you help me on this one (what is the number of steps)
Code: Select all
 . . . | 9 . 3 | . . .
 . . 3 | 2 . 7 | 4 . .
 . 7 . | . . . | . 8 .
-------+-------+-------
 7 8 . | . . . | . 3 4
 . . . | . . . | . . .
 6 4 . | . . . | . 5 1
-------+-------+-------
 . 1 . | . . . | . 4 .
 . . 7 | 3 . 6 | 9 . .
 . . . | 8 . 9 | . . .

Just to be sure I understand the rules of the game.
Thanks.
JPF
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Postby gsf » Wed Mar 22, 2006 4:47 pm

vidarino wrote:Hmm, not from where I'm standing, I'm afraid...

try the ones marked F only
but if you order N before F you will get different counts from mine
vidarino wrote:(Note that I'm "borrowing" your one-letter step codes... ;-) )

no problem

my solution is shorter than yours arguments have a better
chance of reaching consensus than my solution is longer
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Postby Ruud » Wed Mar 22, 2006 5:13 pm

JPF wrote:Hi Vidarino , Hi Ruud

Could you help me on this one (what is the number of steps)
Code: Select all
 . . . | 9 . 3 | . . .
 . . 3 | 2 . 7 | 4 . .
 . 7 . | . . . | . 8 .
-------+-------+-------
 7 8 . | . . . | . 3 4
 . . . | . . . | . . .
 6 4 . | . . . | . 5 1
-------+-------+-------
 . 1 . | . . . | . 4 .
 . . 7 | 3 . 6 | 9 . .
 . . . | 8 . 9 | . . .

Just to be sure I understand the rules of the game.
Thanks.
JPF

I counted 13 steps

These are the steps (N means naked single):

Code: Select all
 1: R6C5=3, R6C4=7N
 2: R7C4=5N,R6C3=9
 3: R7C6=2N,R7C1=9, R2C2=9, R4C5=9
 4: R5C5=2, R7C5=9N,R6C6=8N
 5: R6C7=2, R3C9=9, R5C8=9
 6: R4C3=2, R3C7=3, R4C7=6N
 7: R4C4=1N,R3C1=2, R4C6=5, R5C4=6, R7C7=8N
 8: R3C6=1, R7C9=3, R3C4=4, R5C6=4, R5C7=7N,R1C3=8, R5C9=8, R8C1=8
 9: R5C3=1, R1C1=4, R8C5=4, R9c3=4, R7C3=6, R2C5=8
10: R2C1=1, R8C8=1, R9C5=1, R3C3=5N,R1C2=6, R3C5=6
11: R1C7=1, R1C5=5, R2C9=5, R9C7=5N,R2C8=6N
12: R8C9=2N,R9C1=3N,R5C1=5, R8C2=5, R9C9=6
13: R1C8=2, R9C2=2, R5C2=3, R1C9=7, R9C2=7


Ruud.
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Postby ab » Wed Mar 22, 2006 6:24 pm

vidarino wrote:My solver, and I believe ab's too, counts like this;
1. locate singles (naked or hidden) - but don't place any numbers
2. place all located singles in one sweep
3. rinse and repeat until solved


very nicely put Vidarino, that's exactly what I'm looking for.

gsf wrote:an alternate way of counting would be to incrementally make the moves as they are
found during each scan, which would tend to increase the per-scan count and
decrease the total number of scans, closer I think to what human solvers do


I agree that this way of analysing a grid is not what humans do, but it seems to be the best way of analysing a path of singles objectively. Two human solvers will not take the smae path through a puzzle, since placing one number might uncover several new singles and which one you spot will vary.

Ruud wrote:BTW, I do not see these sudokus as inferior


Neither do I. It was a play on the idea of superior puzzles and also an eye catching thread title for the forum:)
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Postby tarek » Wed Mar 22, 2006 6:32 pm

Finally got it:D ,

Had to tweak the solver for this one....... I searched through my database but nothing was that satisfactory, so I have to generate some more...

Vidar, your last puzzle needed 27 steps on my solver:D

This the toughest I found on the database.... a shy 18 stepper:(
Code: Select all
Tarek #002
 . . 3 | . 2 . | . . . 
 . . . | . 9 . | . 7 . 
 . 6 . | . . . | 4 3 5 
-------+-------+------
 4 . 6 | . . . | . . . 
 7 . . | 3 . 8 | . . 6 
 . . . | . . . | 3 . 2 
-------+-------+------
 1 4 5 | . . . | . 8 . 
 . 9 . | . 6 . | . . . 
 . . . | . 8 . | 5 . . 

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Postby ab » Wed Mar 22, 2006 8:05 pm

I've updated the puzzles list on the first post and decided that puzzles need 15 steps to qualify. I might regret that, maybe it should be 20 steps, but then none of my puzzles would qualify.

Only 2 of gsf's lst of puzzles qualify, but they are worthy contenders, each taking 20 steps.

So far vidarino has the most steps, 27 with this puzzle:

Code: Select all
puzzle #11 (vidarino) 27 steps
+-------+-------+-------+
| 2 . . | 9 8 . | . . . |
| . 7 6 | . . . | . . . |
| . . . | . . . | 4 2 . |
+-------+-------+-------+
| 3 . 8 | . 4 . | . 1 . |
| . . 4 | . 9 . | 3 . . |
| . 6 . | . 2 . | 9 . 4 |
+-------+-------+-------+
| . 3 5 | . . . | . . . |
| . . . | . . . | 8 4 . |
| . . . | . 6 7 | . . 3 |
+-------+-------+-------+
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Postby Ruud » Wed Mar 22, 2006 8:27 pm

If the puzzles would require at least 20 steps, I can offer these:

Code: Select all
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000200000350601000068000009030000420000482000014000090500000130000703062000004000
087005009000001000300090040054009000000070000000600810060010005000500000800300670
000046000080002300600000052769000003000000000800000916930000001004300020000750000
060002000005006900000048070002000037800000006750000200090150000006200300000400090
004500000060010820090000500000007200056000930008900000009000050037050040000002300
000630100053007080010000000008000059700090006140000700000000060030500270007023000
009003060000005400025000000004020009008040600600090700000000870002100000040900300
000000580002008004071090200100200000000736000000005009004020790900800600018000000
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500000000170003000000100485046800000000070000000005870253001000000400092000000003
400018000700003500056000200009005000080000010000700600004000950001600002000930007
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030000000201050000700000023006300800910000067003002100490000008000070609000000070
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080200040060803090200400000107000300000000000006000105000001009040907080070005010
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091000000000070930007600000300002000510000047000500003000008300072090000000000180
290006000000050070300002400004200900070000040006007500009700001050080000000500083
062000180000400000003908000007000408100050003308000200000106800000007000076000320
109000600200300000000760000300000005804090306600000004000072000000004009005000103
800400007007000000010008430005000069600030005730000200064100080000000600900005002
060000201008700009000032004050070000000603000000090030900420000700001400105000080
800003100010800030000070005000001068005000200670900000200080000030002090008600002
001000050000904073000000000008050320030206010042090500000000000970605000050000800
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080000003300000000176050020000260095000000000710049000020080176000000002500000040
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060300000090400800000090602700000500650000073009000008304050000006007010000001050
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002001000000500030470060020000003087020080060350900000090030054040002000000700800

But if you insist on 15 or more, I can submit another 13,000:D

Ruud.
Ruud
 
Posts: 664
Joined: 28 October 2005

Postby ab » Wed Mar 22, 2006 9:11 pm

Yes maybe it should be 20. Also like Tarek maybe people should be limited to 15 puzzles.

I haven't got any 20s the best I can do is 19:

Code: Select all
                 
.9.....7.
2.7.....9
....5..4.
...3.5...
..2...8..
...4.9...
.5..1....
4.....6.8
.6.....9.
ab
 
Posts: 451
Joined: 06 September 2005

Postby vidarino » Wed Mar 22, 2006 10:57 pm

OK, here's one more. It takes 25 steps (or 31, if you count naked and hidden singles separately), and is sneaky enough to open with 5 singles, then a long series of very few singles, before collapsing in the end.

Code: Select all
+-------+-------+-------+
| . . . | . . . | 9 . . |
| . . . | 5 . 8 | . . 4 |
| . 3 . | . 7 . | 1 . . |
+-------+-------+-------+
| . . . | . . 2 | 7 . 6 |
| . 1 . | 4 . 3 | . 9 . |
| 2 . 8 | 1 . . | . . . |
+-------+-------+-------+
| . . 9 | . 8 . | . 4 . |
| 8 . . | 2 . 6 | . . . |
| . . 2 | . . . | . . . |
+-------+-------+-------+


And another one, which only needs 21 steps, but might be of interest since it only contains 20 givens;
Code: Select all
+-------+-------+-------+
| . 8 4 | . . . | . . . |
| . 9 . | . . . | . . . |
| . . . | . . 6 | 1 . 4 |
+-------+-------+-------+
| 5 . 7 | 6 . . | . . . |
| 4 . . | . . . | . . 5 |
| . . . | . . 3 | 6 . 9 |
+-------+-------+-------+
| 2 . 6 | 1 . . | . . . |
| . . . | . . . | . 5 . |
| . . . | . . . | 3 8 . |
+-------+-------+-------+


And a 23-step one that starts off with only solitary singles;
Code: Select all
+-------+-------+-------+
| . . . | . . . | 5 . 4 |
| . . . | . 2 . | . 1 . |
| 2 9 . | 5 . . | . . 3 |
+-------+-------+-------+
| . 4 . | . 3 . | 6 . . |
| 6 . . | 4 8 1 | . . 5 |
| . . 8 | . 5 . | . 4 . |
+-------+-------+-------+
| 8 . . | . . 3 | . 9 6 |
| . 3 . | . 7 . | . . . |
| 1 . 6 | . . . | . . . |
+-------+-------+-------+


I have a few more tucked away (some 1600 puzzles requiring 20+ steps:) (but no more 25+, hrmph...) ), but I'll see if I can single out (har har) some of the more interesting ones.

Vidar
vidarino
 
Posts: 295
Joined: 02 January 2006

Postby JPF » Thu Mar 23, 2006 5:18 pm

Thanks Ruud, for the explanations.

Well, living not far from Monte Carlo doesn’t help.
Like ab, I’m stuck with 19 steps (using Vidarino’s way of counting).

In addition, the puzzle is ugly, but does have some symmetry :
Code: Select all
Puzzle JPF #B01

 4 7 . | 9 . . | . . 5
 . 6 9 | 7 . . | 3 8 .
 . . 2 | 5 . . | . . .
-------+-------+-------
 3 . . | . . 1 | 5 . .
 . . . | . . . | . . .
 . . 5 | 6 . . | . . 8
-------+-------+-------
 . . . | . . 7 | 8 . .
 . 8 4 | . . 5 | 9 2 .
 7 . . | . . 6 | . 5 4

19 Steps : 5,2,2,3,2,3,2,2,1,3,3,4,1,1,1,5,6,4,3

I’ll try again.

JPF
JPF
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Posts: 3752
Joined: 06 December 2005
Location: Paris, France

Postby Ruud » Thu Mar 23, 2006 5:33 pm

I just discovered a new 25-stepper in my latest batch of sudokus.

The solving path is pretty narrow for the first 40 placements.

Code: Select all
Ruud 25#2
. . .|. . 2|4 . .
. . 2|. 4 .|. 8 5
. 6 .|. . 3|7 . .
-----+-----+-----
9 . .|. 7 .|. 5 .
. . .|. . .|. . .
. 7 .|. 5 .|. . 4
-----+-----+-----
. . 3|6 . .|. 7 .
5 4 .|. 3 .|1 . .
. . 8|1 . .|. . .


I wonder what would be submitted if there were no symmetry requirement...

Ruud.
Ruud
 
Posts: 664
Joined: 28 October 2005

Postby gsf » Thu Mar 23, 2006 5:57 pm

Ruud wrote:I wonder what would be submitted if there were no symmetry requirement...

these 2 (non-symmetric) can be solved with naked singles only
each with 34 batched naked single steps

Code: Select all
. . 3 | . 5 . | 6 . .
4 . . | 1 8 9 | . . 7
7 8 . | . . . | . . .
------+-------+------
2 . 4 | . . . | . . 1
. . 8 | 6 . 1 | . . 5
. . 1 | . . . | . . .
------+-------+------
. . . | . . 8 | 9 . .
. . 5 | . . 4 | . . .
9 . . | . . . | 2 . .


. 2 3 | . . . | 6 8 .
. . . | 1 . 9 | . . .
. 8 . | . . . | 4 . .
------+-------+------
. . . | . . 1 | . 6 .
6 . . | . . . | 5 3 .
9 . 5 | . 3 . | . . 7
------+-------+------
. 1 . | 2 . . | . . .
5 . . | 7 . . | . . .
8 . . | . . . | . . 3
gsf
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Location: NJ USA

Postby vidarino » Thu Mar 23, 2006 6:21 pm

Here's a nice one that is solved in 21 steps by the current counting method, and 39(!) steps if hidden and naked singles are "split" (a.k.a. gsf's counting method).:)

Code: Select all
+-------+-------+-------+
| . 1 . | . . . | 7 . . |
| . . 3 | . . 1 | . . . |
| . . 9 | . 3 . | . 1 6 |
+-------+-------+-------+
| . . . | . 2 . | 9 4 . |
| 5 . . | 1 . 9 | . . 8 |
| . 6 2 | . 5 . | . . . |
+-------+-------+-------+
| 7 4 . | . 6 . | 3 . . |
| . . . | 2 . . | 4 . . |
| . . 5 | . . . | . 6 . |
+-------+-------+-------+


Vidar
vidarino
 
Posts: 295
Joined: 02 January 2006

Postby JPF » Thu Mar 23, 2006 7:34 pm

I only found 2 non-symmetric 27-steppers in the 17s list from gfroyle :
Code: Select all
000080200010000500030000040000603400800000000700000000000100007000000089200060000
200060800000001300000075000050000071003800000000000000470000050000400200000000000


JPF
JPF
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