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i cannot complete easy

 
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PostPosted: Wed Sep 07, 2005 4:53 pm    Post subject: i cannot complete easy Reply with quote

Sad anybody help
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Wed Sep 07, 2005 6:02 pm    Post subject: Please be more specific Reply with quote

Hi! I'd like to help you, but I need a little more information. Which puzzle are you talking about? dcb Confused
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PostPosted: Thu Sep 08, 2005 2:11 pm    Post subject: Reply with quote

most of them, lol sudoku easy and medium, i cannot seem to complete it
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Thu Sep 08, 2005 4:16 pm    Post subject: Let's start with today's Daily Sudoku Reply with quote

OK, since you don't care where we start, let's start with today's puzzle.

7 x x | 1 5 x | x x 8
x x 4 | x x 2 | x x x
x x x | x x 4 | 5 6 x

6 x x | x x x | x 2 9
5 x 2 | x x x | 8 x 4
3 4 x | x x x | x x 1

x 3 8 | 6 x x | x x x
x x x | 2 x x | 9 x x
1 x x | x 8 7 | x x 3

Let's start by thinking about the number "5". You can see that there's a "5" in the first row, and that there's another "5" in the third row. But there's no "5" in the second row, and there's no "5" in the upper left 3x3 box. So we can be certain that a "5" must appear either in row 2 column 1 or in row 2 column 2 -- it can't go in r2c3, because there's already a "4" in that spot.

But it can't go in r2c1, either, because of the "5" in r5c1. The only spot left is r2c2, which must be a "5":

7 x x | 1 5 x | x x 8
x 5 4 | x x 2 | x x x
x x x | x x 4 | 5 6 x

6 x x | x x x | x 2 9
5 x 2 | x x x | 8 x 4
3 4 x | x x x | x x 1

x 3 8 | 6 x x | x x x
x x x | 2 x x | 9 x x
1 x x | x 8 7 | x x 3

Now it's your turn. Can you find the next number in this puzzle? dcb
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alanr555



Joined: 01 Aug 2005
Posts: 193
Location: Bideford Devon EX39

PostPosted: Thu Sep 08, 2005 7:56 pm    Post subject: Reply with quote

> I cannot complete easy
> anybody help

> OK, since you don't care where we start, let's start with today's puzzle.

7 x x | 1 5 x | x x 8
x x 4 | x x 2 | x x x
x x x | x x 4 | 5 6 x

6 x x | x x x | x 2 9
5 x 2 | x x x | 8 x 4
3 4 x | x x x | x x 1

x 3 8 | 6 x x | x x x
x x x | 2 x x | 9 x x
1 x x | x 8 7 | x x 3

> Let's start by thinking about the number "5".

Why start with "5" and not some other digit?

Randomly there is an 11% chance of starting with "5". There are three
occurrences of "5" but FOUR occurrences of "8" and so it cannot be that
the choice is the digit with the highest frequency of occurrence.

+++

I am getting to grips with the logic - but it takes so long to implement
and I go to sleep part way through the process and then have to apply
again (when I wake up) checks that I probably already undertook.

Carol Vorderman advises that she can solve the Fiendish puzzle in just
seventeen minutes and has a target time for this of ten minutes.

Speed (combined with accuracy) must depend on knowing where to look
(ie being able to "sense" patterns from an overall scan) - rather than
applying a logical sequence of procedures like a computer would.

How does one train oneself to sense such patterns quickly?

+++
> Now it's your turn. Can you find the next number in this puzzle?

Is there really A (unique) NEXT number?

Surely the next number to emerge will depend upon the technique
selected by the user, will it not?

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PostPosted: Thu Sep 08, 2005 11:01 pm    Post subject: Reply with quote

yes thnxs, i can get alot of numbers in the grid but then it just goes wrong , it does this to me everytime, i write 1-9 on a paper and i check them if they r in the box or line veritcal and horizontal, is this a technique
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Fri Sep 09, 2005 3:48 pm    Post subject: Sudoku Techniques Reply with quote

Anonymous wrote:
yes thnxs, i can get alot of numbers in the grid but then it just goes wrong , it does this to me everytime, i write 1-9 on a paper and i check them if they r in the box or line veritcal and horizontal, is this a technique


OK, I guess you'd like to learn some techniques for solving Sudoku puzzles.

I suppose each solver has his own style. I'll just describe the way I usually attack a puzzle. Maybe that will work for you. Maybe not. At least it's a start.

-- I print the puzzle using my computer. I like spreadsheets, so I've set up a grid that's shaded gray and white, to make it easy for me to concentrate on the 3x3 boxes. If one copy of the puzzle gets too cluttered, or if I make a mistake, I can easily print a new copy.

-- I always start by scanning for simple combinations of two or three numbers that tell me exactly where a single digit has to go, like the situation with "5" I described in an earlier message.

-- I do this systematically, starting with rows 1 - 3, continuing with rows 4 - 6, and ending with rows 7 - 9. Then I look at the columns the same way.

-- Anytime I locate a new number I check to see if it gives me a clue about where to place another number. Particularly rewarding is the case where placing one digit leads to a chain of deductions that allow me to place all 9 instances of that digit. This happens a lot, especially on the "Easy" puzzles.

-- Anytime I have as many as six numbers in a single row, column, or 3x3 box, I stop to analyze the three missing numbers. This often allows me to complete the row or column, as in the example partially illustrated below.
Code:

 x  2  x  4  5  6  x  8  9
 x  x  x  x  x  x  1  x  x
 x  x  x  x  x  x  3  x  x
 3  x  x  x  x  x  x  x  x

I'm sure you can see how this works -- I'm missing just three numbers in the first row, and they are {1, 3, 7}. I can't put a "1" or a "3" in the seventh position, so clearly a "7" has to go there. Now I'm just missing {1, 3}, and since "3" can't go in the first position, a "1" has to go there, leaving "3" as the only possibility in the third position.

-- A situation that's a little harder for me to spot looks something like this next example:
Code:

 x  2  x  4  5  6  x  8  9
 x  x  x  x  x  x  x  x  x
 7  x  x  x  x  x  x  x  x
 x  x  1  x  x  x  x  x  x

I get to the same result as in the previous situation, but the reasoning is a liitle different -- I have to notice that, since I can't have two "7"s in the same 3x3 box, the "7" can only fit in the seventh position.

-- I don't usually use an auxiliary table to keep track of unresolved possibilities -- I just make extra marks on the puzzle. Sometimes I have a situation like this:
Code:

 x  x  x  x  x  x  1  2  3
 x  x  x  7  x  x  x  x  6
 x  x  x  x  x  x  *  8  9

In this example the 3x3 box on the right is missing just 3 digits, {4, 5, 7}. Clearly the "7" has to go in the cell marked *. But I can't tell where to put the "4" or the "5". So I just mark two cells as 4/5, to remind myself that these two values have to appear in these cells, in some order:
Code:

  x    x    x    x    x    x    1    2    3
  x    x    x    7    x    x   4/5  4/5   6
  x    x    x    x    x    x    7    8    9

I write these possibilities on the puzzle using small letters at the top of each cell where I have located a "pair" of values. On the easy puzzles, this is usually as far as I have to go. On harder puzzles I may have to mark triplets of values, like this:
Code:

   x     x     x     x     x     x     1     2     3
   x     x     x     7     x     x   4/5/6 4/5/6 4/5/6
   x     x     x     x     x     x     7     8     9


-- If I can't find a row, column, or 3x3 box with six numbers filled in, I look for one with five numbers, then for one with four, etc. I try not to make too many of the auxiliary marks on the puzzle too soon -- I tend to get confused if I make too many marks. So I try to find all the pairs first, then the triplets, and so forth.

-- From there, it's just a matter of being sure I don't make any mistakes, and of analyzing the ways the various possibilities interact with each other.

I don't know if any of this will help, but I hope it does. dcb Smile
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PostPosted: Fri Sep 09, 2005 6:05 pm    Post subject: Reply with quote

yes thanxs very much i apreciate it
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