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sudoku: test yourself

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RichD

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May 12, 2008, 7:18:55 PM5/12/08
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Below is a puzzle, solved by champion
Thomas Snyder in 2:36. I spent 23 minutes.


_ _ _ _ _ _ 4 6 _
_ _ _ _ _ 3 _ _ 9
_ 8 4 _ _ 7 _ _ 1

2 _ _ _ _ _ 7 1 _
5 _ 3 8 _ _ _ 9 _
9 _ _ 1 _ _ 5 3 _

_ 2 5 _ _ 8 _ _ 6
_ _ _ _ _ 2 9 8 5
_ _ _ _ _ 5 _ _ 7


I don't believe he has a method, he must
do a lot of guessing... but how does one guess
consistently correctly?


--
Rich

RichD

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May 12, 2008, 7:22:37 PM5/12/08
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On May 12, RichD <r_delaney2...@yahoo.com> wrote:
> Below is a puzzle, solved by champion
> Thomas Snyder in 2:36. I spent 23 minutes.


snip

> I don't believe he has a method, he must
> do a lot of guessing... but how does one guess
> consistently correctly?


oops, correction:

_ _ _ _ _ _ 4 6 _
_ _ _ _ _ 3 _ _ 9
_ 8 4 _ _ 7 _ _ 1

2 _ _ _ _ _ 7 1 _

5 _ 3 8 _ _ _ _ _


9 _ _ 1 _ _ 5 3 _

_ 2 5 _ _ 8 _ _ 6
_ _ _ _ _ 2 9 8 5
_ _ _ _ _ 5 _ _ 7


--
Rich

Gene Wagenbreth

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May 12, 2008, 7:51:39 PM5/12/08
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RichD
Took me 8 minutes. Its easy to imagine someone thinking 3 times
faster than I do.

G

tho...@antispam.ham

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May 12, 2008, 8:05:30 PM5/12/08
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RichD <r_dela...@yahoo.com> writes:

>> Below is a puzzle, solved by champion
>> Thomas Snyder in 2:36. I spent 23 minutes.

> snip

>> I don't believe he has a method, he must
>> do a lot of guessing... but how does one guess
>> consistently correctly?

No guessing was required. Process of elimination works just fine.

Richard Heathfield

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May 13, 2008, 12:31:36 AM5/13/08
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RichD said:

> Below is a puzzle, solved by champion
> Thomas Snyder in 2:36. I spent 23 minutes.
>

<snip>

> I don't believe he has a method, he must
> do a lot of guessing... but how does one guess
> consistently correctly?

By having a method.

The solution took me around 15 minutes, with no guessing, and without using
any sophisticated techniques (X-wing, Y-wing, and so on - not because I'm
above that sort of thing, but because I can never remember how they work).

So - despite being completely useless at Sudoku - I shaved eight minutes
off your time. I don't have any difficulty whatsoever in believing that
someone who is actually good at it can shave off a further twelve or so.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

RichD

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May 13, 2008, 12:41:07 AM5/13/08
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On May 12, tho...@antispam.ham wrote:
> >> Below is a puzzle, solved by champion
> >> Thomas Snyder in 2:36.  I spent 23 minutes.
> > snip
> >> I don't believe he has a method, he must
> >> do a lot of guessing... but how does one guess
> >> consistently correctly?
>
> No guessing was required.  Process of elimination works
> just fine.

That's how I did it... there's no way to
use elimination to get under 5 minutes.


--
Rich

RichD

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May 13, 2008, 12:44:24 AM5/13/08
to
On May 12, Richard Heathfield <r...@see.sig.invalid> wrote:
> > Below is a puzzle, solved by champion
> > Thomas Snyder in 2:36.  I spent 23 minutes.
>
> <snip>
>
> > I don't believe he has a method, he must
> > do a lot of guessing... but how does one guess
> > consistently correctly?
>
> By having a method.
>
> The solution took me around 15 minutes, with no guessing, and without using
> any sophisticated techniques (X-wing, Y-wing, and so on - not because I'm
> above that sort of thing, but because I can never remember how they work).
>
> So - despite being completely useless at Sudoku -
> I shaved eight minutes off your time. I don't have any difficulty
> whatsoever in believing that
> someone who is actually good at it can shave off a further twelve or so.

I find it unimaginable.

What does that mean, "good at it"? What method
exists, that would shave another 12 minutes?

--
Rich

Richard Heathfield

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May 13, 2008, 12:52:10 AM5/13/08
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RichD said:

That may be true, or it may not be true, but you have not demonstrated it
to be true.

Richard Heathfield

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May 13, 2008, 1:04:43 AM5/13/08
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RichD said:

> On May 12, Richard Heathfield <r...@see.sig.invalid> wrote:

<snip>

>> So - despite being completely useless at Sudoku -
>> I shaved eight minutes off your time. I don't have any difficulty
>> whatsoever in believing that
>> someone who is actually good at it can shave off a further twelve or so.
>
> I find it unimaginable.

I find it unimaginable that people could bring themselves not only to be in
the same room as Tetley's Bitter, but even to *drink* it. And yet they do.

> What does that mean, "good at it"?

Adept at solving Sudoku puzzles.

> What method exists,

A number of advanced (non-guessing but nevertheless not immediately
obvious) Sudoku techniques exist. I mentioned some of them in my last
reply. This grid is so simple that it requires none of them.

> that would shave another 12 minutes?

Faster thinking. For example, in my own solution I was held up for a good
three minutes because a really simple, obvious fact (7 goes HERE, duh) was
staring me in the face but I just didn't see it. Once I eventually spotted
it, the implications followed faster than I could write them down. Someone
who can quickly spot the blindingly obvious could have saved three minutes
right there.

I don't see why you think it so unlikely that someone else could actually
be better at this than you or me. I solved it in fifteen, and I could feel
the minutes sliding by. I knew I was taking far longer than I ought to (as
I always do with Sudoku). I write computer programs reasonably quickly. It
is pleasant for me to imagine that I write them more quickly and more
correctly than Thomas Snyder. We all have different skills. Not everyone
is a Sudoku champion. You'd expect a Sudoku champion to be good at Sudoku,
wouldn't you?

Jussi Piitulainen

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May 13, 2008, 4:47:34 AM5/13/08
to
RichD writes:

> Richard Heathfield wrote:
>> So - despite being completely useless at Sudoku -
>> I shaved eight minutes off your time. I don't have any difficulty
>> whatsoever in believing that
>> someone who is actually good at it can shave off a further twelve
>> or so.
>
> I find it unimaginable.
>
> What does that mean, "good at it"? What method
> exists, that would shave another 12 minutes?

I know nothing about any methods but I know from experience that one
learns to simply see patterns: this column is missing 4 and 8, the 3
and 5 on this row must be in that box, those three boxes are 1, 7 and
8 so that one must be 4, things like that. Think of the 9 you removed
as a correction: no thinking required to put it back, the 9's in the
neighbouring columns force it at a glance.

One learns to use numbers that are not there yet: one of these three
is 5 so there can be no 5 over there; these two are 2 and 3, therefore
those two are 7 and 9.

And one remembers what were missing where. When one gets a box down,
two or three other boxes go down without thinking, like dominoes. One
has already thunk of them, no need to think again, just write the
answers down.

That's how it feels when it goes smoothly. This one was smooth.

The Qurqirish Dragon

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May 13, 2008, 10:31:13 AM5/13/08
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I did it in 7:35, using notepad (very slow compared to writing, but I
didn't want to waste a sheet of paper). I figure that at least a
minute or two were used simply to move the cursor and delete
underscores. This puzzle is definitely one that can be done as fast as
you can physically write the digits., so I don't find a 3-minute time
at all unreasonable.

Nick Wedd

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May 13, 2008, 11:50:16 AM5/13/08
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In message
<1e2db37d-0421-4db0...@m45g2000hsb.googlegroups.com>, The
Qurqirish Dragon <qurqi...@aol.com> writes

Agreed. This is a particularly easy specimen. (It took me 17 minutes,
but I'm pretty useless at sodukus.) You don't need a "method" for it,
you just fill in the cells until you find it is complete.

For a well-written list of methods, as needed for more difficult
sodukus, see http://www.brainbashers.com/sudokuhelp.asp

Nick
--
Nick Wedd ni...@maproom.co.uk

Richard Heathfield

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May 13, 2008, 12:02:47 PM5/13/08
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Nick Wedd said:

> [...] I'm pretty useless at sodukus.

I do try not to spelflaim, but on this occasion I have to ask whether that
apparently serendipitous misspelling of "sudokus" is deliberate. :-)

Dogstar

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May 13, 2008, 3:45:54 PM5/13/08
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"Richard Heathfield" <r...@see.sig.invalid> wrote in message
news:bMmdnUK4PtMiJ7TV...@bt.com...

> Nick Wedd said:
>
>> [...] I'm pretty useless at sodukus.
>
> I do try not to spelflaim, but on this occasion I have to ask whether that
> apparently serendipitous misspelling of "sudokus" is deliberate. :-)
>
> --
> Richard Heathfield

How many different ways can you misspell pseudo-cuss?

-Dogstar


Gib Bogle

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May 13, 2008, 5:11:36 PM5/13/08
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Richard Heathfield wrote:
> Nick Wedd said:
>
>> [...] I'm pretty useless at sodukus.
>
> I do try not to spelflaim, but on this occasion I have to ask whether that
> apparently serendipitous misspelling of "sudokus" is deliberate. :-)
>

I've found that many people mispronounce the word as "soduku". It's
similar to way "hara-kiri" becomes "hari-kari".

Phil Carmody

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May 13, 2008, 5:29:50 PM5/13/08
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Many, in particular if we can include names such at the
internet and real-world loon supremo Koos (Nolst Trenite).
(Which of course is completely OT ;-) .)


Sudoku always reminds me of the xkcd classic:

kus
no, I'm a polite chappy
sudokus
shit!

Phil
--
Dear aunt, let's set so double the killer delete select all.
-- Microsoft voice recognition live demonstration

Dogstar

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May 13, 2008, 8:45:48 PM5/13/08
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"RichD" <r_dela...@yahoo.com> wrote in message
news:c7db61e6-1b82-4df7...@b5g2000pri.googlegroups.com...
> Rich

One has to be fast if one uses Sudoku Toilet Paper:

http://www.adminpick.com/a-little-fun-with-with-toilet-paper/11/01/

-- Dogstar


James Waldby

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May 13, 2008, 10:30:00 PM5/13/08
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On Wed, 14 May 2008 00:29:50 +0300, Phil Carmody wrote:
> "Dogstar" <Dog...@microprizes.com> writes:
>> "Richard Heathfield" <r...@see.sig.invalid> wrote in message
>> news:bMmdnUK4PtMiJ7TV...@bt.com...
>>> Nick Wedd said:
>>>> [...] I'm pretty useless at sodukus.
>>>
>>> I do try not to spelflaim, but on this occasion I have to ask whether
>>> that apparently serendipitous misspelling of "sudokus" is deliberate.
>>> :-)
>> How many different ways can you misspell pseudo-cuss?
>
> Many, in particular if we can include names such at the internet and
> real-world loon supremo Koos (Nolst Trenite). (Which of course is
> completely OT ;-) .)

> Sudoku always reminds me of the xkcd classic:
>
> kus
> no, I'm a polite chappy
> sudokus
> shit!
>
> Phil

I don't recall whichever xkcd you refer to. That
aside, here's a sudoku a little easier than the one
posted earlier in this thread: http://xkcd.com/74/

For those who might think http://xkcd.com/149/ has
something to do with sudoku, note that the sudo in
it is nothing to do with sudoku but instead is a
Unix command, equal to "Super user says to do".

-jiw

Richard Heathfield

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May 14, 2008, 2:42:44 AM5/14/08
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Dogstar said:

<snip>


>
> One has to be fast if one uses Sudoku Toilet Paper:
>
> http://www.adminpick.com/a-little-fun-with-with-toilet-paper/11/01/

9+ minutes, for the one pictured. I think this is *such* a bad idea!

bi...@y7mail.com

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May 14, 2008, 6:15:14 AM5/14/08
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0:4:23

RichD

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May 15, 2008, 10:08:17 PM5/15/08
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On May 14, bi...@y7mail.com wrote:
> > Took me 8 minutes. Its easy to imagine someone
> > thinking 3 times faster than I do.
>
> 0:4:23

Really? Remarkable.

Please describe your method,
and/or sequence.

--
Rich

Big LN

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Jun 17, 2008, 12:46:13 AM6/17/08
to

Heaps of practice (I do several a day). Just like a crossword puzzle or chess,
I'm 'seeing' the next parts of the solution as I'm writing in the current number.
That's actually a slow time as I was wasting time 'looking' for more complex
method patterns.

'Onya

Jon Haugsand

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May 2, 2009, 3:41:16 PM5/2/09
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RichD <r_dela...@yahoo.com> writes:

You cannot sincerely mean that this puzzle was difficult?

--
Jon Haugsand
Dept. of Informatics, Univ. of Oslo, Norway, mailto:jon...@ifi.uio.no
http://www.ifi.uio.no/~jonhaug/, Phone: +47 45 00 39 94

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