Sunday 25 December 2011

SU-DO-KU


Sudoku
Sudoku is a logical puzzle game, originally created in puzzle books and then made available in countless newspapers worldwide.
Many people are put off by seeing a grid with numbers in it, but in fact the puzzle doesn't require any arithmetic at all - just deduction and logic.
What is a Sudoku?
There's plenty of discussion about what consitutes a Sudoku puzzle, but many Sudoku fans agree:
  • A Sudoku should have 30 or less initial values filled in out of the 81 total
  • Sudoku should be solvable by entirely logical deduction - no guesses should be needed. (That doesn't mean that you can't use guesswork, just that you shouldn't have to.
  • For aesthetic reasons, a Sudoku should have rotational symmetry - the positions of the initially filled in cells should be the same if you were to turn your page round.
  • The Sudoku must only have one solution!
Of course, for beginner puzzles, often there are more than 30 values filled in - this is just to give you a head start while you're learning!
Many people think that harder Sudoku puzzles are the ones with less values filled in to begin with. While this is often the case, there are plenty of frustratingly difficult puzzles available with 28 or more cells filled in - difficult because they really require you to use lots of different solving techniques to complete them.

How to Play Sudoku?

Sudoku requires no calculation or arithmetic skills. It is essentially a game of placing numbers in squares, using very simple rules of logic and deduction. It can be played by children and adults and the rules are simple to learn.

Sudoku Objective

The objective of the game is to fill all the blank squares in a game with the correct numbers. There are three very simple constraints to follow. In a 9 by 9 square Sudoku game:
  • Every row of 9 numbers must include all digits 1 through 9 in any order
  • Every column of 9 numbers must include all digits 1 through 9 in any order
  • Every 3 by 3 subsection of the 9 by 9 square must include all digits 1 through 9

Similarly, smaller Sudoku puzzles, such as the 4x4 puzzle, must have the numerals 1 through 4 in each row, column and subsection. Larger Sudoku games (16 by 16) must have numerals 1 through 16 in each row, column and region. The principles are the same whatever the size of the game.
Every Sudoku games begins with a number of squares already filled in, and the difficulty of each game is largely a function of how many squares are filled in. The more squares that are known, the easier it is to figure out which numbers go in the open squares. As you fill in squares correctly, options for the remaining squares are narrowed and it becomes easier to fill them in. The Sudoku games on SudokuDaily.net let you check your progress as you go, to help prevent going down a wrong path.

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