The basic elimination method is a method to solve problems by using the rule that the number 1 ~ 9 can only appear once in each row, column and room. Basic exclusion methods can be divided into row exclusion method, column exclusion method and nine-square exclusion method. The actual solution process is as follows: (1) Find the solution of nine squares; (2) It is found that there is only one number left in the position where a nine-square grid can be filled; That is, I found the filling position of the number in the nine squares. Find the column exclusion solution: find the case where only one number can fill a column; This means that the filling position of the number in this column has been found. Looking for exclusive solutions: looking for a situation where only one number can be filled in a row; This means that the filling position of this line of numbers has been found. The lifting method of foundation exclusion method is block exclusion method, which is one of the most commonly used methods in intuitive method.

Unique solution

When a column has eight cells filled with numbers, the only number that can be filled in the remaining cells of the column is the number that has not yet appeared. It becomes the only solution of a series. When the number of cells in the nine-grid reaches 8, the remaining cells in the nine-grid can only be filled with numbers that have not yet appeared. Become the only solution of Jiugongge.

Congruence solution

The congruence solution is that the number that can be added to a cell has been excluded, so the number of this cell can only be added to the number that does not appear.

Block exclusion method

Block exclusion method is a generalization of basic exclusion method and one of the most commonly used methods in intuitive method.

Residual test method

The so-called remainder test method is a problem-solving method of adding the values of the remaining cells when there are more numbers in a row or a column and there are two or three remaining cells.

Implicit unique candidate number method

When a number appears only once among the candidate numbers of each cell in a column, it is the only candidate number in the column. The value of this cell can be determined as this number. This is because according to the rules of Sudoku, each column should contain the number 1 ~ 9, and the candidate numbers in other cells do not contain this number, so it cannot appear in other cells, so it can only appear in this cell.

Triple chain number deletion method

The method of finding out no more than three different numbers in a column, a row or a nine-grid candidate, and then deleting these three numbers from the candidates in other grids is called the three-chain number deletion method.

Implicit triple chain number deletion method

In a row, there are three numbers in the same cell, but none of the other cells in the row contain them. We call this number pair the invisible triple chain number. Then other numbers in the candidates of these three cells can be excluded. When the invisible triple chain number appears in a column of nine cells, The processing method is exactly the same, ........................................................................................................................................................................... We call this number pair the invisible triple chain number. Then all other candidates of these three squares can be excluded. When the hidden triple chain number appears in a column or nine squares, the treatment method is exactly the same, or the method of "finding out the situation that a number only appears in a row, a column or a three-square candidate number, and then deleting the candidate numbers of these three squares into these three numbers" is called the hidden triple chain number deletion method.

Rectangular vertex deletion method

The rectangular vertex deletion method is the same as the rectangular exclusion method mentioned in the intuitive method. Rectangular vertex deletion method is not easy to find in recognition, so it is better to use other methods first.

Triple chain deletion method

The triple chain deletion method is an extension of the rectangular vertex deletion method. If you are not clear about the rectangular vertex deletion method, you can refer to the rectangular vertex deletion method to make it easier to understand the contents of this section. Find out the situation that a number only appears in the same three rows of a certain three columns, and then delete the number from the candidates of other squares in these three rows; Or the method of "finding a number that only appears in three columns with the same three rows, and then deleting this number from other candidates of these three columns" is called triple-chain column deletion method.

Key number deletion method

In the later stage of solving problems, when the above-mentioned unique candidate number method, hidden unique candidate number method, block deletion method, number pair deletion method, hidden number pair deletion method, triple chain number deletion method, hidden triple chain number deletion method, rectangular vertex deletion method and triple chain column deletion method can not make progress, the key number deletion method can be considered. The key number deletion method is to find a number that only appears twice in the row (or column, nine squares) in the later stage. Suppose this number is in one of the lattice classes, continue to solve it, and if there is an error, determine our hypothetical error. If it is still difficult to continue solving, let's assume that this number is in another cell and see if we can get an error. This is the key number reduction method.

Edit this paragraph exclusion method

When a column, a row or a palace has been filled with seven numbers, you can use the exclusion method to exclude the numbers that cannot appear in this cell, so as to determine what numbers should be filled in the cell. For example, a row has been filled with 1, 3, 4, 5, 7, 8, 9, and there are 2, 6 left. One of the blank columns has 2, so it can't be 2 in this blank, so it must be 2 in another blank, so it must be 6 in this blank. When a column, a row or a palace has been filled with six numbers, the exclusion method can also be used.

Edit this paragraph's anamorphic Sudoku overview.

Today, Sudoku has developed into various types. If subdivided according to different conditions, there are no fewer than 100 species, and the number is still increasing. We can usually have common metamorphosed Sudoku, such as diagonal Sudoku, sawtooth Sudoku, killer Sudoku and so on. diagonal sudoku

Sawtooth sudoku

Killer Sudoku

The so-called deformed Sudoku is a new Sudoku problem formed by changing some standard Sudoku conditions or rules. Some morphed Sudokus also have multiple morphed conditions at the same time, and the morphed conditions are as follows: 1, 4-word solitude, 6-word solitude, 16-word solitude, 25-word solitude, etc. Depending on the number of numbers used; 2. The categories of restricted areas can be diagonal Sudoku, extra area Sudoku, rainbow Sudoku, etc. 3. There is zigzag Sudoku when the uterus changes; Multiple Sudokus are superimposed on Siamese Sudoku, Samurai Sudoku and Super Sudoku. 4. Replacing known numbers with other elements includes alphabet Sudoku, dice Sudoku and numeral Sudoku. 5. Using the sum or product of numbers in cells, there are killer Sudoku, boundary Sudoku, arrow Sudoku, Rubik's Cube Sudoku, arithmetic Sudoku and so on. 6. There are continuous Sudoku, unequal Sudoku, Fortress Sudoku, Fifteen Sudoku and Black and White Sudoku. Use the numerical relationship in adjacent cells; 7. Numeric attributes of limited cells include odd-even Sudoku, large, medium and small Sudoku, etc. 8. The prompt numbers other than Sudoku include edge observation Sudoku and skyscraper Sudoku. 9, according to the prohibition of the same digital position, Sudoku, Sudoku without horses, etc. ; 10, non-square Sudoku includes ring Sudoku, cube Sudoku, hexagon Sudoku, cell Sudoku, etc. 1 1, as well as three-in-one sudoku, two-grid sudoku and so on, need the cooperation of multiple sudoku conditions to solve the problem. The above 1 1 categories are not all conditions of change, but common categories, and there are many examples of deformed Sudoku. In fact, the condition of deformation is unlimited. As long as you have imagination, you can create your own new Sudoku. Although the conditions of Sudoku vary widely, one absolute condition remains unchanged-duplicate numbers cannot appear in the same restricted area. As long as this condition is met, there is no separation from the category of "Sudoku".