Sudoku is a mathematical game that originated in Switzerland in the18th century. It's a logic game with paper and pen. Players need to infer the numbers of all remaining spaces according to the known numbers on the 9×9 disk, and ensure that the numbers in each row, column and thick line palace (3*3) contain 1-9, which is not repeated.
Sudoku is nine palaces, and each palace is divided into nine squares. Give some known numbers and problem-solving conditions in this eighty-one box, and use logic and reasoning to fill in the numbers of 1-9 in other blanks. Make each number of 1-9 appear only once in each row, column and palace, so it is also called "Jiugongge".
Advanced solution:
The above methods are called basic methods, and all other methods are called advanced methods, which are a supplement to the basic methods, so they are also called auxiliary methods.
Advanced solutions include locking candidates, subsets/tuples, X-wings and unique rectangles.
Binary universal grave, X chain, multi-bit chain and other digital chains with advanced skills. Nearly a hundred methods have been developed.
Among them, the first three methods plus basic solution are the methods introduced and used in general Sudoku books, and they are also the skills that most people can understand and master.