The highlighted cell in the sudoku below has the following candidate values 1,3,5,6. There are several approaches to solve this wellliked puzzle. Emeritus professor of mathematics jerry janusz presents a survey, stepbystep, of most of the known techniques used in solving sudoku puzzles and illustrates them with many examples so that the casual solver may learn to complete some of the hard puzzles. The book begins with a description of three elementary techniques that will allow the reader to solve easy and medium sudoku puzzles. It seems impossible, with just a 9 in row 1 and another in column 2 that immediately affect box 1. This candidate must reside in each of the three rows and share the same three columns or vice versa. It is important to understand that all sudoku puzzles require an iterative approach. Mensa guide to solving sudoku download ebook pdf, epub. Sudoku is a logic game that can help to keep our brains fresh and active. An essential killer sudoku solving technique is the 45 rule. In other words, no number may appear more than once in any row, column, or block. A naked pair also known as a conjugate pair is a set of two candidate numbers sited in two cells that belong to at least one unit in common.
Sudoku solutions solver and helper play thousands of free. Almostlocked set analysis can be extended to grids. A swordfish pattern occurs when three rows or three columns each contain 2 or 3 cells that hold a matching locked candidate. Theyre listed in roughly increasing order of complexity from the simple and obvious, to the advanced and complex. All correctly formed sudoku puzzles are solvable using logical solving techniques.
What is the underlying mathematics and logic behind some solution techniques. Hundreds of puzzles plus techniques to help you crack them all longo, frank, gordon, peter on. Solving a hard sudoku puzzle will require quite a different set of techniques compared to an easy one. The current paper explains and compares three algorithms for solving sudoku puzzles. Looking for number pairs one of the first advanced sudoku solving techniques that you might want to try is to start with one number at a time starting with the number 1 and look for instances where two of the same number appear within the same set of three squares. Sudoku is not just a mathematical or arithmetic type of puzzle. The scanning technique is also very useful for hard puzzles up to the point where no further progress can be made and more advanced solving techniques are required.
Top nine most often used strategies for solving expert sudoku. Introduction to sudoku contrary to what many people believe, sudoku didnt actually originate in japan. Many sudoku puzzles have dark lines separating the nine threesquarebythreesquare boxes for easy identification. Sudoku swordfish is a variation of the xwing pattern. I have tried to pitch you the two most successful ways of solving sudoku, that has also helped me. There are 8 different deductive techniques that sudokusolver will point out for you when they are available.
Looking for number pairs one of the first advanced sudoku solving techniques that you might want to try is to start with one number at a time starting with the number 1 and look for instances where two of the same number appear within the. Sudoku solver killer sudoku solving techniques and tips. Sudoku is interesting both as a logical exercise what are good strategies for. The more advanced techniques that follow are only required to solve very high level, intense puzzles. You dont need any maths, and you dont need to guess. Such aitype sudoku solving programs tend to be a thousand to a million times slower than straightforward backtrack. To solve a regular sudoku puzzle, place a number into each cell of the diagram so that each row across, each col umn down, and each block within the larger diagram there are 9 of these will contain every number from 1 through 9. Top nine most often used strategies for solving expert. Solving techniques for sudoku basic fish xwing, swordfish, jellyfish.
Be sure to have a personal introduction at the beginning, including sma. Hundreds of puzzles plus techniques to help you crack them all. In our first example we will focus on box 2, which like any other box in sudoku must contain 9. But look more carefully and youll see that the 9 in row 8 precludes any 9 in row 8 of box 7. That is they reside in the same row, box or column. There are eightyone cells on the board, which is broken j. The bottom line is that sudoku is a fascinating new puzzle game that has taken the world by surprise and storm.
If you do not know how to play sudoku puzzles, you can find the rules here relatively easy sudoku puzzles can be solved by a sequence of eliminations eliminations of all impossibilities. The basic layout of the sudoku grid is much like a chess game or crossword puzzles. You will need new specialised killer sudoku solving techniques to progress in these puzzles besides the standard sudoku techniques you will already know. These are some of the techniques that can be used to solve sudoku puzzles. Solving sudoku puzzles is easier than it looks, and all but the very hardest puzzles can be solved using just a few simple techniques. Here you will find several techniques that we have been compiling that we hope will help you solve sudokus better and faster. Some of the most exciting logic is yet to come topics in this section. It is however the only cell in the box which has 3 as a candidate value, therefore the 3 must go in this cell. Mar 04, 2017 please visit my channel and check out my other uploads such as how to solve a sudoku puzzle a tutorial, or next nine sudoku strategies beyond the top nine most often used if you havent done so. As you know, the numbers from 1 to 9 must be placed once in every block. The sudoku assistant uses several techniques to solve a sudoku puzzle.
Sudoku puzzle can contain only one instance of each number. You can solve the puzzle completely, partially or solve a single cell using the buttons in the solving section of the features block. Click download or read online button to get mensa guide to solving sudoku book now. He provides twentyfive pages of instruction for beginners to sudoku puzzle solving and ninety pages for more advanced players. Killer sudoku adds a new dimension to standard sudoku, requiring arithmetic to solve. Sudoku solver implements a variety of logical deductive techniques to solve sudoku puzzles.
Then more advanced methods that depend on candidates are presented. An exhaustive study on different sudoku solving techniques. An x wing is a technique for removing candidates pencil marks. Swordfish this is very similar to using xwings, in that it will allow you to use knowledge about rows to remove candidates from columns, and vice versa. Sudoku became popular in japan in 1986 under the name of sudoku, and it has just started to actually become popular in the u. Finding the candidates to eliminate is where advanced solving techniquescalled deductionscome in. You complete the puzzle when all of the cells have been filled in with corresponding numbers. It is clear that the solution will contain those values in those two cells we just dont know which is which at this stage and all other candidates. It starts with either two parallel rows or two parallel columns.
Many published sudokus wont require any technique beyond hidden subsets, but the more advanced techniques are often useful against the very hardest puzzles. Since there must be a 9 in both row one and row eight, but they cannot occupy the same column, it follows that either the topleft and bottomright marked cells contain the 9s, or the bottomleft and topright cells do. Learn how to solve any sudoku puzzles with amazing high quality video tutorials. Puzzles range in difficulty from easy to very challenging. In the sudoku puzzle below, the only cells in rows one and eight that can contain a 9 are those coloured green. To complete the sudoku puzzle requires a lot of patience as well as the ability to think logically. The grid is also divided into nine 3x3 subgrids named boxes which are marked box 1 through box 9. Almostlocked set analysis can be extended to grids, where it forms the basis for all finned fish and sashimi, and also to what i am calling. Sudoku solutions solver and helper play thousands of. The sudoku puzzle reached craze status in japan in 2004 and the craze spread to the uk through the puzzle pages of national newspapers. Sudoku solving techniques download free ebooks in pdf at. If you have already practiced and conquered all of the techniques up til now, or youre simply too enthralled in this to heed my warning, then by all means read on.
There are two main techniques one can use to solve a sudoku puzzle. Techniques for solving sudoku sudoku is a puzzle involving logic no arithmetic or guessing is required. A pencilandpaper algorithm for solving sudoku puzzles. However the difficult ones need more logic involved. Sudoku grid consists of 81 squares divided into nine columns marked a through i, and nine rows marked 1 through 9. When utilizing these techniques, the way the pros prefer to do it, is to start with the basic ones. This site is like a library, use search box in the widget to get ebook that you want. However, there is no doubt that the word has been adopted into modern parlance, much like crossword.
You are currently armed with enough knowledge to solve 95% or more of the sudoku puzzles currently published in newspapers, books, and magazines the more advanced techniques that follow are only required to solve very high level, intense puzzles. Solving sudoku puzzles is one of the most popular pastimes in the world. If you have more ways in mind, feel free to share your techniques too in the comment section. If you do not know how to play sudoku puzzles, you can find the rules here. It works just as well if the numbers are substituted with letters or other symbols. Crook is professor emeritus of computer science, winthrop university, rock hill, sc.
You can solve the puzzle completely, partially or solve a single cell using the buttons. Please visit my channel and check out my other uploads such as how to solve a sudoku puzzle a tutorial, or next nine sudoku strategies beyond the. Enter the numbers of the puzzle you want to solve in the grid. An exhaustive study on different sudoku solving techniques abstract sudoku is the japanese abbreviation of a longer phrase, suuji wa dokushin ni kagiru, meaning the digits must remain single. Below is a description of each, in order of their complexity. Sudoku solving techniques when you are stuck works 100%. The daily telegraph uses the name sudoku, but you may see it called su doku elsewhere. Relatively easy sudoku puzzles can be solved by a sequence of eliminations eliminations of all impossibilities. How to solve sudokus an index of sudoku solving techniques. Its all done by observation and logic, and the most important thing is to stay 100% accurate at all times. Learn how to solve sudoku puzzles with little effort. Sudoku solving techniques ebook download in pdf format. The hidden pair solving technique is an intermediate solving technique. It is a very popular puzzle that trains our logical mind.
Human style solving techniques for sudoku implemented in hodoku a sudoku generatorsolveranalyzer written in java. The basic idea of completing puzzles is to find cells the small squares where you are sure that only one value is a valid placement. These two techniques are simple, straightforward, reliable, and sufficient in solving most standard sudoku puzzles. Make sure youre happy with why xwings work before moving on to swordfish.