SU-DO–KU PUZZLE

– B.UMA, Assistant Professor

Introduction

A Sudoku is a number game with placement of numbers in a grid. The ancient name of the game was “Numbers in Place” & its modern name “Su-Do-Ku” was given by a Japanese Maki Kajii in 1984.The game became popular all over the world since 2005. Nowadays it has become a regular part in many newspapers.

The standard version of Sudoku consists of a 9 x 9 square grid containing 81 cells and it is subdivided into nine 3 x 3 blocks. The aim is to fill all the 81 cells with numbers from 1 to 9 so that each row, each column and each of the nine 3 x 3 grids contains all the digits from 1 to 9 exactly once. That is no number from 1 to 9 is repeated in any row or column (although, it can be repeated along the diagonals).

There are many variations in Sudoku namely Classic Sudoku, Mini Sudoku, Mega Sudoku, Cross Sums Multi Sudoku, Daigonal Sudoku and Odd Even Sudoku.

Sudoku Rules

1. Each row, column, and nonet can contain each number (1 to 9) exactly once.(A nonet is a 3 x 3 grid).

2. The sum of all numbers in any row, any column or any nonet must be equal to the small number printed in its corner. For traditional Sudoku puzzles the sum is equal to 45.

Sudoku Techniques

1. Scanning Technique

The scanning technique is usually used to solve easy puzzles. Here are some ways of using scanning techniques:

? Scanning in one direction

? Scanning in two directions

? Searching for Single Candidates

? Eliminating numbers from rows, columns and boxes

? Searching for missing numbers in rows and columns

2. Analyzing techniques

For hard Su-Do-Ku puzzles, pencil marking technique is used which is a systematic process of writing small numbers inside the squares to denote which ones may fit in. The solver must analyze the results, identify special number combinations and deduce which numbers should be placed where. Here are some ways of using analyzing techniques:

? Eliminating squares using Naked Pairs in a box

? Eliminating squares using Naked Pairs in rows and columns

? Eliminating squares using Hidden Pairs in rows and columns

? Eliminating squares using X-Wing

Example

Question :

8

4 1 5 3

2 9 4 5 1 8

4 1 2

6 2

3 2 9

6 9 3 5 8 7

5 4 8 1

3

Answer:

3 1 5 8 2 7 9 4 6

4 6 8 9 1 5 7 3 2

7 2 9 3 4 6 5 1 8

9 4 6 5 3 8 1 2 7

5 7 1 6 9 2 4 8 3

8 3 2 1 7 4 6 9 5

6 9 3 2 5 1 8 7 4

2 5 7 4 8 9 3 6 1

1 8 4 7 6 3 2 5 9

Conclusion

Using simple logic and the basic strategies we will be able to solve just any sudoku puzzle. As you work on more puzzles, you will come up with your own approaches and strategies. It’s all a matter of finding and cultivating your own sense of sudoku logic.

SU-DO–KU PUZZLE

– B.UMA, Assistant Professor

Introduction

A Sudoku is a number game with placement of numbers in a grid. The ancient name of the game was “Numbers in Place” ; its modern name “Su-Do-Ku” was given by a Japanese Maki Kajii in 1984.The game became popular all over the world since 2005. Nowadays it has become a regular part in many newspapers.

The standard version of Sudoku consists of a 9 x 9 square grid containing 81 cells and it is subdivided into nine 3 x 3 blocks. The aim is to fill all the 81 cells with numbers from 1 to 9 so that each row, each column and each of the nine 3 x 3 grids contains all the digits from 1 to 9 exactly once. That is no number from 1 to 9 is repeated in any row or column (although, it can be repeated along the diagonals).

There are many variations in Sudoku namely Classic Sudoku, Mini Sudoku, Mega Sudoku, Cross Sums Multi Sudoku, Daigonal Sudoku and Odd Even Sudoku.

Sudoku Rules

1. Each row, column, and nonet can contain each number (1 to 9) exactly once.(A nonet is a 3 x 3 grid).

2. The sum of all numbers in any row, any column or any nonet must be equal to the small number printed in its corner. For traditional Sudoku puzzles the sum is equal to 45.

Sudoku Techniques

1. Scanning Technique

The scanning technique is usually used to solve easy puzzles. Here are some ways of using scanning techniques:

? Scanning in one direction

? Scanning in two directions

? Searching for Single Candidates

? Eliminating numbers from rows, columns and boxes

? Searching for missing numbers in rows and columns

2. Analyzing techniques

For hard Su-Do-Ku puzzles, pencil marking technique is used which is a systematic process of writing small numbers inside the squares to denote which ones may fit in. The solver must analyze the results, identify special number combinations and deduce which numbers should be placed where. Here are some ways of using analyzing techniques:

? Eliminating squares using Naked Pairs in a box

? Eliminating squares using Naked Pairs in rows and columns

? Eliminating squares using Hidden Pairs in rows and columns

? Eliminating squares using X-Wing

Example

Question :

8

4 1 5 3

2 9 4 5 1 8

4 1 2

6 2

3 2 9

6 9 3 5 8 7

5 4 8 1

3

Answer:

3 1 5 8 2 7 9 4 6

4 6 8 9 1 5 7 3 2

7 2 9 3 4 6 5 1 8

9 4 6 5 3 8 1 2 7

5 7 1 6 9 2 4 8 3

8 3 2 1 7 4 6 9 5

6 9 3 2 5 1 8 7 4

2 5 7 4 8 9 3 6 1

1 8 4 7 6 3 2 5 9

Conclusion

Using simple logic and the basic strategies we will be able to solve just any sudoku puzzle. As you work on more puzzles, you will come up with your own approaches and strategies. It’s all a matter of finding and cultivating your own sense of sudoku logic.