Showing posts with label Sudoku. Show all posts
Showing posts with label Sudoku. Show all posts

Thursday, March 3, 2011

SUDOKU - learning and playing the game


I have two kids and both have highly diverse interests. So, each is enrolled for extra curricular activities, in different places. As the session is in progress for one, the other remains with me and during the waiting hours, both are keen to play games on my cell phone.

I seldom use the instrument except to send an urgent SMS or make an emergency call when out of home. But these young fellows, they have identified other options and speak about them!

In my Nokia 2630, Sudoku is an available option in the games folder.

One day as my younger one played with the same, I simply peeped in. I felt there was something wrong in the way in which she moved ahead in the game. I got the cell, read the instructions and tried playing the game. Wahl!my trial was successful. We got an emoticon displaying CORRECT!

My elder kid was already familiar with the same as she used to play it with her aunty. Though she can play for herself, she could not explainthe basic points to be considered and hence couldn't guide her sibling effectively.

Earlier my younger one thought it was something related to Mathematics and so kept herself off, as she is yet to learn addition and subtraction. however, as she came to know about it, she has become so interested that she is quite eager to fetch the morning newspaper and search for Sudoku in it.Though its a higher level, she facilitates me to fill in as much as I can. She verifies for the answers where available and gets excited for all the right entries.
There are small books with Sudoku puzzles for kids in any book stall.

 What is a Sudoku?
It is a logical number placement puzzle in which we enter a digit from 1 to 9 in each cell of a 9x9 grid made up of 3x3 sub grids, starting with various digits given in some cells. Each row and column must contain only one instance of each digit. As we enter into the game option, there are three categories, Easy, Medium and Hard. The basic procedure is the same.

Naturally I took the Easy segment. There were 100 puzzles in that alone.

Easy simple grid:
The first one was as tabulated below.
2

1
6
3
4

4
6
2
5

1
2
5

6
3
4
6
3
5

2

1
4

2
6
6
3
2
1

5

This game is like filling up the blanks. The numbers used in this grid ranges from 1 to 6. Now I named the cells based on position in the rows and columns for identification.
R1 C1
R1 C2
R1 C3
R1 C4
R1 C5
R1 C6
R2 C1
R2 C2
R2 C3
R2 C4
R2 C5
R2 C6
R3 C1
R3 C2
R3 C3
R3 C4
R3 C5
R3 C6
R4 C1
R4 C2
R4 C3
R4 C4
R4 C5
R4 C6
R5 C1
R5 C2
R5 C3
R5 C4
R5 C5
R5 C6
R6 C1
R6 C2
R6 C3
R6 C4
R6 C5
R6 C6

In Row 1, only RIC2 was blank. The missing number was 5 in that row. All other numbers from 1 to 6 were present in other cells. 

In row 3, only R3C4 was missing and the left out number was 4 and in row 4, the missing one was R4C5 and the value was 1.

Similarly in the last row, only R6C5 was missing and the missing number in that line was 4.
This seemed so easy.

2
5
1
6
3
4

4
6
2
5

1
2
5
4
6
3
4
6
3
5
1
2

1
4

2
6
6
3
2
1
4
5

In the remaining two rows there were two cells each with missing values. How to find that?
I calculated the total sum of all values in the complete rows and columns. Both ways it was 21.
Now I started concentrating attention into columns. Last column had only one left out value. Cell R2C6. The number was 1.

In the 4th column the cell was R5C4 and the value 3.
2
5
1
6
3
4

4
6
2
5
1
1
2
5
4
6
3
4
6
3
5
1
2

1
4
3
2
6
6
3
2
1
4
5

Now only column 1 was left to be filled.  Here in the second row, the missing value was 3 and in the fifth row, the missing value was 5.
2
5
1
6
3
4
3
4
6
2
5
1
1
2
5
4
6
3
4
6
3
5
1
2
5
1
4
3
2
6
6
3
2
1
4
5

Addition of all values in every row and column gave 21. Thus the Sudoku was completed and the answer was right!

So, this is how we play a Sudoku? The number range would differ and also the sum total also with each Sudoku. This is only demonstration of a simple one for beginners.  

This helps kids to learn through fun. It helps them to identify missing numbers, addition and subtraction. It improves their comprehensive ability, concentration and confidence. Read more about Sudoku and its logic, mathematics, variants, etc at: http://en.wikipedia.org/wiki/Sudoku

Standard grids:
Sudoku is generally in a 9x9 grid format in which the sub grids are units of 3x3.


8


5
3
6
4
9

4
7
9
2
8

6
3

5
3
6



2
8
1
9
6
8
4
5
3





3
1

7
8





6
2
8
9
5
3
3
2
1



5
4
8

8
4

1
5
7
2
9

9
5
8
4
2


6

 An example on how I proceeded to solve the above Sudoku is elaborated below.
R
O
W
S

Columns

C1
c2
C3
C4
C5
C6
C7
C8
C9
R1
8
1
2
5
3
6
4
9
7
R2
4
7
9
2
8
1
6
3
5
R3
5
3
6
9
7
4
2
8
1
R4
9
6
8
4
5
3
1
7
2
R5
2
5
3
1
9
7
8
6
4
R6
1
4
7
6
2
8
9
5
3
R7
3
2
1
7
6
9
5
4
8
R8

6
8
4
3
1
5
7
2
9
R9

7
9
5
8
4
2
3
1
6

Naturally the sum of numbers 1 to 9 along a row or column would be 45.
In columns C3 AND C7, only two numbers are missing.
In C3, the numbers 2 and 7 are missing. In R6, we have 2 in C5. So the probable value for C3R6 is 7.
In C7, the numbers 1 and 3 are missing. Here also, in R4, we have 3 in C6R4. So the most probable entry here is 1.

Now let us move to rows.
 In R1, R2, R4, R6, R8, R9 only two numbers are missing.
R1: here 1 and 7 are missing. But number 1 is available in C9R3 and number 7 in C2R2.
So it is easy to note the numbers here.
R2: the missing numbers are 1 and 5.
Here again 1 is already available in R3C9 and 5 is available in C6R8.
So it is easy to note the numbers.
R4: the missing numbers are 2 and 7.
The number 2 is already available in C8 and 7 in C9. So entry of numerals is again an easy task.
In R6, the missing numbers are 1 and 4.
Of this 1 is in C2 and 4 is in C1. So again numbers is easy.
In R8, the missing numbers are 3 and 6. Here also 6 are there in C4 and 3 in C1.
In R9, the missing numbers are 1 and 7.Here again 1 is already there in C1 and 7 in C8.
So the entry is quite easy.

At this stage let us move to columns once again. As we span them, we can see that C1, C2, C8 and C9 have only one missing number each. So, let us fill them soon with the respective missing number from 1 to 9. (Entries are highlighted in yellow).

Now rows R3 and R7 remains to be filled. So let us move back to rows.
In R3, numbers 4, 7, 9 are missing. But 4 are available in C4 and 7 in C6. So let’s enter 4 and 7.
In R7, numbers 6, 7, 9 are missing. But 6 are in C4 and 7 are in C6. So let us enter these numbers 6 and 7.
These entries are highlighted in blue.
Now we can enter 9 comfortably in C4R3 and C6R7. (Entries highlighted in green.)
The only box that is left blank is R5C5, waiting for another 9.(entry highlighted in pink).
This completes the Sudoku.

There is another method of approaching the same Sudoku through sub-grids. This is elaborated in the link http://www.sudokudaily.net/instructions/ . Here we can also play Sudoku online, daily at different levels.


9

5





8
4


5
7

1

6

2
7
6



4


9
6


3
5
1
2
7

4

1

3


2
1

9
8



4

8
1


4

9

3


8



5
1


2


7

6


In this Sudoku,let us combine all available options.This is a sample from the Nokia category Hard(level1).
Initially let us divide the Sudoku into sub grids of 3x3 units.(Better use a sketch pen to demarcate thus in the beginning.)
In each sub grid the numbers 1 to 9 can appear only once.As earlier, in any column or row also, the numbers 1 to 9 can appear only once.
Now, let us start the process by identifying the column or row or sub grid that has least number of blanks and start filling them one by one. As we proceed, we can see that the rows or columns with many balnks are reduced to minimum blanks and are automatically easy to be filled in.
 
The resolved puzzle is added for cross reference...


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

Another sample from Nokia 2630 set of Medium category Sudoku, done giving emphasis to the sub grid style.
try yourself and check out the answer key beneath.

3
1
2

9
5
4
7
6
5

9
1

7

8
2
4

7
2
6
3
5


9


7


2
4


2
8

1


9
3

3

9
8
2

5
7

4
5
6



3
1
1
7

3
5
8
9

4
8
9
3
4
2

7

5

Answer key for verification

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


There are many sites that explain about Sudoku, its logic, steps and methods with tips. Some of them are noted below. Visit them for more Sudoku.  
http://www.sudokuessentials.com/how_to_play_sudoku.html

On You tube there are many videos that explain about this puzzle resolving game. A sample is brought below.

1.       How to play a Sudoku


Another simple guide on types of Sudoku, strategies in Sudoku and a tutorial is also available at eHow. http://www.ehow.com/how_2041470_play-sudoku.html. They say it improves your memory and strengthens your brains.


At the next level, an excellent video of the same is available as 8 segments, at Monkey see. This covers the following topics in a simple manner.
VIDEO ON HOW TO PLAY SUDOKO, LEVEL 2 

1.       How to play a Sudoku

2.       Basic rules of Sudoku

3.       Guess work in Sudoku

4.       One choice technique

5.       One place technique

6.       Scanning technique

7.       Double scanning technique

8.       Finishing the puzzle

ENTER THE WORLD OF PUZZLES AND ENJOY SOLVING SUDOKU…
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