The New Sudoku Players' Forum

by **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

by **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

by **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

by **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.

by 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

by **tarek** » Wed Mar 22, 2006 6:32 pm

Finally got it

,

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

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 . .

Tarek

by 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 | +-------+-------+-------+

by **Ruud** » Wed Mar 22, 2006 8:27 pm

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

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910008700800007010002000000008000040000895000050000300000000200030100004009200065 000046300008900040000000600076000100030070090001000480003000000050004700009510000 060300000090400800000090602700000500650000073009000008304050000006007010000001050 057300000000040050402000001300060400000283000009050002500000804010030000000001590 000000030000004500096010080000020107300050006204060000070080620005900000080000000 000208030010000090004300500070000059300000001840000070002006700050000020090804000 002001000000500030470060020000003087020080060350900000090030054040002000000700800

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

Ruud.

by 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.

by **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

by **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

by **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.

by **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

by **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

by **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

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