Sudoku has occurred from Japanese "sou" - number and to "dock" - nearby, standing separately. Sudoku are well-known Japanese puzzles where in a square 9х9 cages it is necessary to place numbers in a special way.
Sudoku it is known as the Japanese entertainment, however not only Japan is the native land of this game. Though the idea Sudoku has come not from Japan, but the game name has the Japanese origin. For example, the puzzles very similar on Sudoku, were published since 1892 in the French newspaper Le Siècle. In Japan the puzzle Sudoku has been published by company Nicoly Inc., the large publisher of collections of various puzzles, in newspaper Monthly Nicolist in April, 1984 under heading «the Number can be used only once».
The game history Sudoku totals a millenium. The pattern of Sudoku game was “the Magic square”, appeared in China is 2000 years ago. “The magic square” represents a square in the size 3х3 cages, in each of which one number from 1 to 9 so that the sum of numbers of any column, a line is located and on a diagonal equaled 15.
Development of "the Magic square» has occurred by means of the well-known Swiss mathematician, the mechanic and physicist Leonard Euler. In its works records contain how to form a magic square with certain number of cells, especially 9, 16, 25 and 36. In other document entitled «Scientific research of new versions of a magic square» Euler placed Latin letters (the Latin square) in cages, later it has filled cages with the Greek letters and named a square Greek-Latin. Investigating various variants of a magic square, Euler has paid attention to a problem of a combination of symbols so that not one of them did not repeat neither in one line and nor in one column.
Euler's idea Harward Garis has picked up who in 1979 has published puzzles Sudoku in magazine Word Games magazine. It used a principle of a Latin square of Euler, has applied it in a matrix dimension 9х9 and has added additional restrictions, figures should not repeat and in internal squares 3х3.
Entertaining game quickly extended on the world. In 2004 the British newspaper The Times on the pages has published for the first time a puzzle Sudoku. This publication became sensation, the puzzle has quickly bypassed all Britain, Australia, New Zealand, and also has got popularity and in the USA.
Now there was a set of modifications of Sudoku, but classical Sudoku represents a square 9х9 the cages, broken on subfields with the parties on 3 cages everyone. In some of cages numbers are put in advance down, and the player needs to place missing numbers so that in each column, a line and subfields there were numbers strictly from 1 to 9 and did not repeat. Correctly made Sudoku has only one decision.
Sudoku differ on level of complexity depending on the size of a square. There is very difficult Sudoku in the sizes 15х15 and 16х16 cages. Happen Sudoku in which separate figures for each cage, and the sum of figures of this or that group of cages. Sudoku breaks on some rectangular blocks of the different sizes, and in each field the sum of the figures entering into it is underlined. Also there are Sudoku modifications in which internal blocks not square, and any form, but thus they as a rule include the same 9 cages.