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What is the first thing you do when you start

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What is the first thing you do when you start

Postby imturok on Thu May 07, 2009 7:16 am

For easy and medium games I scan first, mostly starting with 1, but not always. For hard and very hard games I would think first and look for the best entry point.
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Re: What is the first thing you do when you start

Postby lancehoch on Thu May 07, 2009 7:33 am

imturok wrote:For easy and medium games I scan first, mostly starting with 1, but not always. For hard and very hard games I would think first and look for the best entry point.

For easy, I try to find a row, column, or square with only three or four blanks, then I move on to five blanks. I try to not use pencil marks or put two numbers into a cell unless it is absolutely necessary.

For medium, I look for the same three, four, or five blanks, but I also try to keep an eye on specific numbers and scan those quickly if possible. I use more pencil marks, but again, only if necessary.

For hard and very hard I go back to the strategy for easy, but I put in pencil marks everywhere.
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Re: What is the first thing you do when you start

Postby monograptus on Thu May 07, 2009 8:06 am

I'm a bit puzzled here - according to the site rules:

"any sort of tool that gives players artificial advantages in solving sudoku puzzles is strictly forbidden (even pencil & paper)"

So are these pencilmarks in your head or where???

Frankly, I don't see how some puzzles can be solved without writing anything down - [Game]Game 2580 [/Game]for example. If you work through it, you end up with 11 unsolved cells, 10 of which are arranged in five sets of paired cells each of which has two possible solutions, and all the pairs of cells are interdependent with other pairs. Even with pencil and paper, it takes me longer (much longer) to work through the possible solutions from this end-game position than the winner took to do the whole thing from the very start. I'd be fascinated to know what logical approach was used there....
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Re: What is the first thing you do when you start

Postby gwendolyn on Thu May 07, 2009 9:59 am

If you put more than 1 number in a cell, it shows up smaller, and is called "a pencil mark". Then you can backspace the ones you don't need later. The rules are referencing using anything other than the game window.
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Re: What is the first thing you do when you start

Postby monograptus on Thu May 07, 2009 11:09 am

Ah, I didn't realise that - I thought there was only space for a single digit.
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Re: What is the first thing you do when you start

Postby imturok on Thu May 07, 2009 3:44 pm

monograptus wrote:Ah, I didn't realise that - I thought there was only space for a single digit.

I know you can put even 3 digits, I do not know what is the max.
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Re: What is the first thing you do when you start

Postby WaterlooMathie on Thu May 07, 2009 4:49 pm

monograptus wrote:Frankly, I don't see how some puzzles can be solved without writing anything down - [Game]Game 2580 [/Game]for example. If you work through it, you end up with 11 unsolved cells, 10 of which are arranged in five sets of paired cells each of which has two possible solutions, and all the pairs of cells are interdependent with other pairs. Even with pencil and paper, it takes me longer (much longer) to work through the possible solutions from this end-game position than the winner took to do the whole thing from the very start. I'd be fascinated to know what logical approach was used there....


The logical approach is to fill in the cell with 3 choices and fill it with the number that can go in any one of the three squares. So when you get to a similar situation, it only takes seconds to solve instead of minutes.
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Re: What is the first thing you do when you start

Postby lancehoch on Thu May 07, 2009 10:46 pm

imturok wrote:I know you can put even 3 digits, I do not know what is the max.

The max is 9.
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Re: What is the first thing you do when you start

Postby gauravkorde on Sun May 10, 2009 5:21 am

monograptus wrote:Frankly, I don't see how some puzzles can be solved without writing anything down - [Game]Game 2580 [/Game]for example. If you work through it, you end up with 11 unsolved cells, 10 of which are arranged in five sets of paired cells each of which has two possible solutions, and all the pairs of cells are interdependent with other pairs. Even with pencil and paper, it takes me longer (much longer) to work through the possible solutions from this end-game position than the winner took to do the whole thing from the very start. I'd be fascinated to know what logical approach was used there....


The technique is called BUG... http://www.brainbashers.com/sudokuhelp.asp
There are many other techniques also not mentioned on this site... but you don't require those as they are time consuming... its always better to guess if you don't find anything till an XY-wing or a BUG...!!
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Re: What is the first thing you do when you start

Postby strmckr on Sun May 10, 2009 5:26 am

the list of stuff not mentioned is endless.

yes

it is often easier to guess on puzzles with limited amounts of depth.

Never guess! Only make moves based on logical deductions.


its also amusing to read this on the strategy page.

when a large number of world ranked players even admit they use t & e to solve quickly.

the game number Game 2580
which is puzzle:
906007300001003000000010006604908030000401000070306209700060000000500600002700108

requires
for one path choice:
42 naked/hidden singles.

then you find the hardest move:
a skyscraper.
Code: Select all
.-----------.----------.------------.
| 9   25@ 6 | 8  4   7 | 3   1  25@  |
| 25  4   1 | 6  9   3 | 7-5  8  257 |
| 8   3   7 | 2  1   5 | 4   9  6   |
:-----------+----------+------------:
| 6   25@ 4 | 9  27  8 | 57@  3  1   |
| 25  9   3 | 4  27  1 | 8   6  7-5  |
| 1   7   5 | 3  5  6 | 2   4  9   |
:-----------+----------+------------:
| 7   8   5 | 1  6   4 | 9   2  3   |
| 3   1   9 | 5  8   2 | 6   7  4   |
| 4   6   2 | 7  3   9 | 1   5  8   |
'-----------'----------'------------'

5 in r1c9,r4c7 (connected by r14c2) => r2c7,r5c9<>5

and all singles to the end.

you could use a bug instead if you wish to but there is easier things.

the fun part
is that the skyscraper exists with a short singles chain on the board.
marked with *s

Code: Select all
.---------------------.------------------.---------------------.
| 9      2458@    6    | 28   248    7    | 3     1*     245@  |
| 2458   2458    1    | 268  2489   3    | 4789-5 245789  2457 |
| 23458  23458   3578 | 28   1      2459 | 45789  245789  6    |
:---------------------+------------------+---------------------:
| 6      25@      4    | 9    27     8    | 57@     3     1*   |
| 2358   23589   3589 | 4    27     1    | 578    5678    7-5  |
| 18    7       58    | 3    5*      6    | 2      4*     9    |
:---------------------+------------------+---------------------:
| 7      134589  3589 | 128  6      249  | 459    2459    2345 |
| 1348   13489   389  | 5    23489  249  | 6      2479    2347 |
| 345    34569   2    | 7    349    49   | 1      459     8    |
'---------------------'------------------'---------------------'
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Re: What is the first thing you do when you start

Postby lg49143 on Thu May 13, 2010 2:08 pm

I have to stare at the grid for DECADES OF ETERNITIES to find the first hidden singles.

I need tips, hints and advices how I´ll be able to (better said - I MUST BE ABLE TO...):

solve EVERY VERY HARD SUDOKU in LESS than 10 SECONDS!!!
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Re: What is the first thing you do when you start

Postby rypaci on Thu May 02, 2013 8:03 pm

Hello everyone,

I'm a newbie here but I like playing sudoku.
Thanks for your posts I have learned different strategies to play it now.
I'm not very good at this but I enjoy playing it.
It really exercises my mind.

Ryan
http://rypacimarketingsolution.com/
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