## Solve all

Advanced methods and approaches for solving Sudoku puzzles

### Solve all

SUDOKU – The Solution

I have found that the following instructions will solve any SUDOKU problems

1. First create a 81 square grid using EXCEL
2. Into each of the 81 small square of the grid place the numbers

1 2 3
4 5 6
7 8 9

I can forward an e-mail attachment with this EXCEL 81 square grid as well as a 9 x 9 blank 81 square grid (see below) on request

3. For purposes of explanation call:
a. each small square a ‘1 to 9 group’, there being 81 such
groups
b. each 3 x 3 ‘1 to 9 groups’ a ‘mini-group’, there being 9 such
mini-groups.

Once the grid has been created use the following steps to solve any SUDOKU problem

1. Delete all numbers, apart from the given number, from their ‘1 to 9
groups’
2. Delete the given numbers from their rows, columns and 3 x 3
‘mini-group’
3. For ease of further working transcribe the remaining numbers into a
9 x 9 blank 81 square grid.
4. Identify single solitary number(s) and delete them elsewhere from
their row, column and/or 3 x 3 ‘mini-group’.
5. Identify number(s) that do not occur elsewhere in a row, column
and/or a 3 x 3 ‘mini-group’
eg the 4 in this row 237, 564,18, 239, 67, 123, 479, 58, 29 and then
delete the numbers accompanying that number eg the 5 and 6 in
this example and then
delete that number, viz 4, from a row and/or a column and/or 3 x 3
‘mini-group’ in which it
occurs with other numbers as any row, column or 3 x 3 ‘mini-group’
can only have that number 4 once
6. When two numbers appear together twice in the same row, column
or 3 x 3 ‘mini-group’, those numbers can be deleted from elsewhere
in that row, column or 3 x 3 ‘mini-group’
eg the 2 and 3 from the following row: 23, 237, 564,18, 239, 23, 67,
124, 379.
7. When the same three numbers (abc) appear in the same row,
column or 3 x 3 ‘mini-group’ in any combination eg: ab-bc-ca,
ab-bc-abc, ab-ab-abc, ab-abc-abc, abc-abc-abc etc etc, those
three numbers can be deleted from elsewhere in that row, column
or 3 x 3 ‘mini-group’ eg: 236 in the following row 23, 36, 236, 689,
3479,123789, 2569, 148, 679
8. When a number appears two or three times in the same row or
column of a 3 x 3 ‘mini-group’, but no where else in that 3 x 3
‘mini-group’, it can be deleted from that row or column outside
that 3 x 3 ‘mini-group’
9. Keep repeating steps 4, 5, 6, 7 and 8, working rows, columns and
3 x 3 ‘mini-group’ repeatedly until the problem is solved

At any time transcribe the remaining numbers into a 9 x 9 blank 81 square grid to facilitate further working
Geoffrey

Posts: 3
Joined: 05 June 2005

### Re: Solve all

Geoffrey wrote:I have found that the following instructions will solve any SUDOKU problems

Hi Geoffrey.
Firstly, welcome to the forums.

I fear you haven't tested enough Sudoku .
There are some which require more advanced steps such as X-Wing, Swordfish etc to solve, and others which can't be solved without guesswork.

As an example, how does your excel macro handle this puzzle:
Code: Select all
`1..|...|7...2.|...|5..6..|38.|...-----------.78|...|......|6.9|......|...|14.-----------...|.25|..9..3|...|.6...4|...|..2`
angusj

Posts: 306
Joined: 12 June 2005

I have found that the following instructions will solve any SUDOKU problems

LOL!

How many did you test it on?
Last edited by simes on Sun Dec 11, 2011 2:35 pm, edited 1 time in total.
simes

Posts: 324
Joined: 11 March 2005
Location: UK

Your puzzle has been my undoing
I recant, I recant, I maximally recant

Geoffrey
Geoffrey

Posts: 3
Joined: 05 June 2005

Geoffrey wrote:I recant, I recant, I maximally recant

Welcome to Sudoku ... it has a habit of making us all do that (recanting) from time to time .
angusj

Posts: 306
Joined: 12 June 2005

### Angus'd puzzle

Angus,
I have finally solved your puzzle, but only by finally using trial and error on the 38/38 in the cells with x=8 and y = 8 & 9 coordinates. (I dare say there is a more suitable way to identify them)
Is there a more logical solution?

Geoffrey
Geoffrey

Posts: 3
Joined: 05 June 2005

### Re: Angus'd puzzle

Geoffrey wrote:Is there a more logical solution?

It features as my "Solving with Colors" example on:
http://angusj.com/sudoku/hints.php#colors
angusj

Posts: 306
Joined: 12 June 2005