![]() ![]() ![]() ![]() The same technique should be employed when you reach the stage where guessing seems to be the only option. Remember Ariadne whose ball of string helped Theseus through the Minotaur’s fiendishly complicated labyrinth? That thread enabled Theseus to backtrack when he reached a dead-end. This is the key to solving harder Sudoku puzzles. The best way is to write them in an imaginary grid of 3x3 – 1, 2, 3 are at the top, and 7, 8, 9 are at the bottom – this will help you scan when you need to spot patterns. Also look at the 3x3 box itself in the context of each line, and you will soon spot other cells for which there is only one possible solution – the lone number.īefore long you will run into a brick wall when the obvious missing numbers run out – at this point it is time to start making notes of the possible candidates in each cell. Sooner or later you will come across numbers which could be placed in a number of different cells: at this stage, make small notes in the cells of its possible number candidates – this will prove useful later on. The easiest way to begin is to take each number in turn and scan the rows and columns to find cells where that number is missing: you will quickly be able to start putting numbers into cells. Gentle Sudoku, Moderate Sudoku, Tough Sudoku, and Diabolical Sudoku are the four levels that you can choose from depending on your Sudoku skills, ability to stay patient against the odds, and resilience to Sudoku’s mind-bending torment. If you are just starting off then it is worth bearing in mind that both Sudoku and its evil twin the Killer Sudoku are graded by their level of difficulty. To solve Sudoku puzzles you will need every ounce of logic that you can muster. In fact any set of nine distinct symbols – letters, colours, pictures – could be used. Also, contrary to popular opinion, it is not a number puzzle. The reality of solving a Sudoku puzzle grid can stretch the mind of even the most logical amongst us. The rules are deceptively simple: each row, column and 3x3 box of cells must contain each of the numbers 1 to 9. This is an early 'ultimate puzzle' but this crown has been usurped by the puzzle created by Arto Inkala, which is also in the example list.Sudoku is a great puzzle. With the community's help I hope to extend the documentation here.įor those people wondering why " Escargot" cannot be solved by the solver, there is an article on this special Sudoku here. If you are interested in the concepts behind creation and grading, there is a PDF document here called Sudoku Creation and Grading. Many strategies can be further extended and we do not have a complete theory of all Sudoku puzzles. This strategy list is by no means complete. These are now included for the first time on this site. There are naturally special strategies for Jigsaw and Killers because of their differences. They are definitely worth presenting as a demonstration of people's ingenuity but you will only need to have recourse to them on the extreme puzzles. Do read the introductory articles Introducing Chains and Links and Weak and Strong Links.Įxotic strategies do overlap with chaining ones, but they have a peculiar flavour of their own and some wonderful, if obscure, logic. Thus, for example, Remote Pairs are a subset of XY-Chains that is, XY-Chains is a more general approach of which Remote Pairs are a specific instance. ![]() You will find, if you read through this group, that earlier strategies become part of a more general theory as the theme develops. This theme is all about bi-value (only two candidates left in the same cell) and bi-location (only two occurrences of a particular candidate left in the same unit) pairs and the incredible number of deductions one can make from them. With chaining strategies, there is definitely a theme going through them. ![]()
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