Everything about Sudoku that doesn't fit in one of the other sections
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
gsf
2014 Supporter

Posts: 7306
Joined: 21 September 2005
Location: NJ USA

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
JPF
2017 Supporter

Posts: 3754
Joined: 06 December 2005
Location: Paris, France

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
gsf
2014 Supporter

Posts: 7306
Joined: 21 September 2005
Location: NJ USA

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=810: R2C1=1, R8C8=1, R9C5=1, R3C3=5N,R1C2=6, R3C5=611: R1C7=1, R1C5=5, R2C9=5, R9C7=5N,R2C8=6N12: R8C9=2N,R9C1=3N,R5C1=5, R8C2=5, R9C9=613: R1C8=2, R9C2=2, R5C2=3, R1C9=7, R9C2=7`

Ruud.
Ruud

Posts: 664
Joined: 28 October 2005

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
ab

Posts: 451
Joined: 06 September 2005

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

tarek

Posts: 2803
Joined: 05 January 2006

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 | +-------+-------+-------+`
ab

Posts: 451
Joined: 06 September 2005

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

Code: Select all
`3000000701750900000095003000000000500802310600400000000040092000000806350500000070000059344008002000000090007600000150000000003400000760006000000030070026182000000059000004000000500000064080108600020020305006000420102065000000300000010000087004300800000000071006009000030200016000100000300097000805000030060084000000000600750053000701830000000009400004070095000000500000087001040000930000000006210700084000700300046002000700008003050010000300000500000400001002040090000100050088000700400800600037090040000009000010700003000500200900060000408000050000004005023000900603000760000500010020480000000700400105000300040900100700000004809001000500008900030000000790004000010000016040076000850600900303100054008053000009000060007300000000100000046002000000500070090004020505200000630601050007008000200000060014000000800020030610705060000600000004000008090000000009070000040000000200009070103904007000800050000900000610002010049000004060600300202080000034008020005300000400006000700380007010052000000070000060000020300008530000604000009000004000000015002010006900000800020006000309000207400000095000010304000062000000830100070500060001000400000076080000000000504650000020900300003000800010000100602000009340700000000004052002000830000000107800000040100060050004000000090002008000705000000980300000004900050000001300000950000070300020043005807000000040910047004000509000009800000750000000000000030000600948000052000207004000706190200060020300093000021400500007000000000300020000900000500000548000072000609000700010100094000021300000800000200006000700003010908000000005400070306000700800000200000100800040805000710000000090506040000501000483006000750000500000002000830700000502100060000000200009200080078600070200060000053006000100800004035000200300090402000100300046010000700200050067000008000000000890900780060060004000050061000100000900093002000080003007002500404500000009000007003005000001006000540004002707000500080630010005100090060000040070020000035000000070001970002000006000002500300120005700900310000040000030003490006000000022001000004300060000090870000004003070500000209060030000003906000006000480000020010050004060301700000000090807020000000005630000000009040907000000000360401070002000800017001000000290000070040048060008000200010001058006004000005300000020026000700032000007000004000900050670050700808000400020300807001607000900040000050000081000908000302300000000000009506010070000800500600009001070650000000000000740100040804060009005000007300008050060000600490000300003500800006002070000170000080050006030000007858410200000006000043000090000800100300005000027000010000000509274930000002000700009000013000740200000608000000010607000000050200000502400032000080000900018200400000000000155013000000500078003000000090092000400000085072300000000000600213090005002000050700084100900000040080000000008003000000100763000908000050060007020007005000000084769300000000709000000060208000000040500000000487851000000010030000040095060000200080700042000065000100000000000800016000087000902000400001058007009000006480617030000000000000090000070005140003000002000000000000002078102460000090500000200040003006031050000405300000070604000000410600007092040050006000100000300400300015000190707200000004100008000000900000090000240000000370603500091000600809200000000076000900001000020020000640008340001900005007000050000800093000000000257000000250000080010000050630208006000000300000050010701509000003006000002800000042000000000930400600008009000305002080050306008040070100020010000600705900000000037005000604000070000060804500700003000003710000010000800620401000001000090300080020403009000760020000000406000000108000904080600030700000010200000006007900080050300080000030027068100000100000700002001500200360060000900000700000213094009000006000060100700034000004007000080010002008005030090070006001000090050000068000200509000006008017400000000020700002900003400000500000710000590000207000000000939080010003008000000000000075600000240000860500090001000305700009700000431000000000000040088016000000652000800000000010790000000300800600000009102000000000900037200000051030031209000050000006000007202700030000000000000007000180840000090000003000070956004200010007000000040009000000040603000910205400070509000000080008000000070007000266000300750900000600054000008040002000008040000030001040000058000200000105700800090008010500000000720500408000905000060060204007000040200050100806300000000402090000600000000007035600000907200803000046000000052000070900380100000496050000000000500409300000804063005000000601000046000000000000052000070600000050097010800000620403000097020700020009050100000002000300100000500800040000000803040006000701043000069030050002000060070008004000060000720800000305300008000050020004007000080009006052000070000009000230500006400000085000906020100017000000870000306300010000005000040000000000069702054000008907000600100007950000500300020370000045090826000000000004301000000000305070702061000500008000000000000020000300065070803090800000000030298000007000000314002006083000000000020930206407000000000019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But if you insist on 15 or more, I can submit another 13,000

Ruud.
Ruud

Posts: 664
Joined: 28 October 2005

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

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

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 | . 5 419 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
2017 Supporter

Posts: 3754
Joined: 06 December 2005
Location: Paris, France

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

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 | . . 77 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
2014 Supporter

Posts: 7306
Joined: 21 September 2005
Location: NJ USA

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

I only found 2 non-symmetric 27-steppers in the 17s list from gfroyle :
Code: Select all
`000080200010000500030000040000603400800000000700000000000100007000000089200060000200060800000001300000075000050000071003800000000000000470000050000400200000000000`

JPF
JPF
2017 Supporter

Posts: 3754
Joined: 06 December 2005
Location: Paris, France

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