Killer-Sudoku

Killer Sudoku ( also known as the Sum Sudoku or Samunamupure known ) is a number puzzle that combines elements of Sudoku and Kakuro together. Killer Sudoku are quickly confused with area totals. Killer Sudoku may, however, compared to area totals in a sum no number included twice. Despite the name, Killer Sudokus may be easier to solve than classic Sudoku.

Structure and rules

A Killer Sudoku consists of a subdivided into several equal-sized rectangular blocks rectangle; the blocks in turn are divided into individual fields. In addition, the playing field is divided into several blocks independent of the arbitrarily shaped groups. In each group there is a small number.

Usually Killer Sudokus are still persistent and Sudokus from 3x3 blocks, each containing 3x3. Different methods are used for the identification of blocks and groups, usually a combination of deposit to color and different thick dividing lines.

The fields are now filled with digits so that the following conditions are met:

• Only the digits 1,2,3,4,5,6,7,8 and 9 are allowed
• Each of these numbers must occur exactly once per row, column and block
• The sum of the digits in a group must exactly match the number specified for this group
• A digit may occur more than once in a group

The last rule is uncontroversial in Japan, was not mentioned in the first publications in The Times, which led to the confusion of the reader.

Furthermore, even Killer Sudokus of different size possible, eg with 4x4 blocks, each with 4x4 fields in which the numbers 1 to 16 by analogous rules have to be used as above.

Normally, the solution through the given numbers and will be clearly defined.

History

Killer Sudokus published in Japan as Sudoku variant mid-1990s, where they were known under the name Samunamupure. In the English-speaking world they were introduced in 2005 by the magazine " The Times".

Solution methods

To solve Killer Sudoku trying to enter gradually more and more numbers in the appropriate fields, which then combine to form larger and larger areas.

Simple Killer Sudokus contain groups of only one square that are naturally clear and contain the corresponding number. Furthermore, often can be described by the sum of the specified at all possible numbers in this group Narrow strong. So can only contain the numbers 1 and 2, for example, in the common form of a Killer Sudoku with nine digits per block is a group of two fields and sum 3 and with the sum of 7, only either 1 and 6 or 2 and 5 or 3 and 4 included. By logical reasoning can be so provide the appropriate combination of options for all further sums and for larger areas.

Sometimes numbers can be calculate, rather than to decide on combinations. The sum of all rule- righteous registered numbers in a 3x3 square, a row or a column must always be the same or equal to 45 the total of the numbers 1-9 so. This can be for example a remaining number in a block very quickly calculate.