The numerical puzzle Sudoku was invented by Swiss mathematician Leonard Euler back in the 18th century, but it only gained popularity in the 80s and 90s of the 20th century. The so-called “Latin Square” or “Magic Square” develops attentiveness, logic, analytical thinking. It is also a useful pastime.
Traditional Sudoku is a 9x9 square divided into equal squares with a side of 3 cells. As a result, the whole game is based on a grid of 81 squares. The game has different levels of difficulty, depending on the number of initial written down digits and the method of solution. The rule of the game is the same - write down the digits in the empty cells of the square in the following way: in each row, column and small square these digits must not be repeated.
Besides the classic Sudoku in a 9x9 grid, there are other variants - from 4 by 4 to 25 by 25 cells. There are also variants with additional conditions in the task, areas, with a variety of geometric shapes other than square, etc. Let's take a look at some of the popular varieties.
Types of Sudoku
- Sudoku X
The look of this game is a square, with NxN (most often 9x9) cells. This square consists of N (9) small blocks, which are divided into N (9) small cells. In a few of these cells before the beginning of the game there are numbers written in them.
The player's task is to write numbers from 1 to N (9) in the remaining empty cells of the square. The condition: in each column vertically, in each row horizontally and in each block (9x9) each of the numbers from 1 to N (9) must occur once, without repeats.
And all main diagonals of the Sudoku X puzzle must also have no repeats of numbers.
And all main diagonals of the Sudoku X puzzle must have no repeats of numbers.
- Killer Sudoku
In fact, it is a combination of two varieties - “sudoku” and “kakuro”. Sudoku-killer looks like a regular Sudoku. But unlike the classical variant in killer there are additional areas in which the sum of numbers must be equal to a given number, as in kakuro. When solving, this fact is often used: the sum of all the digits in them always = 45. It will help to calculate the numbers accurately when several shaded areas, except for one cell, are placed in one or more neighboring groups. To do this, subtract the sum of these shaded areas from the number 45 (or from 90, 135, etc., when checking several neighboring groups at once).
- Even-Odds Sudoku
In this type of Sudoku, the player is given information about the even and odd numbers in the cells of the grid. Grid cells with odd numbers are marked with circles.
Your task is to write in the grid the numbers from 1 to 9 traditionally with the condition: in each row and column, as well as in each block, the number must be written in a single variant.
- Killer Sudoku
In this form, the grid of the game contains white and black dots on the borders between cells. A white dot stands when the numbers in the neighboring cells differ by 1. And a black dot means that in the neighboring cells the first number is exactly 2 times bigger than the second one. Between the numbers 1 and 2 (since they fall under both conditions) there can be a black or white dot.
- Sudoku puzzle
Sudoku puzzle is a square whose size = NxN (usually 9 by 9). It consists of N (9) small blocks, which are divided into N (9) cells. Part of the cells are filled with numbers.
The task of this type of game is to write in the empty cells of the square numbers from 1 to N (in this case 9). Provided that in each row horizontally and column vertically, as well as in each block of the square the digit occurs once.
- Sudoku with letters
A modified concept of Sudoku with numbers, where instead of numbers, the grid is filled with letters. This type of game is called “Wordoku”. There are 9 letters involved in the game, similar to traditional Sudoku where 9 numbers are involved. The square of the game itself and the goals remain the same. Here it is also necessary to fill all empty cells of the table with letters according to the rule: each row, row and block-square of 3x3 cells must have all provided letters in a single variant. That is, there can be no repetition of letters in a row, column, or block.
- Samurai
A variation of sudoku called Samurai is five overlapping sudoku grids. The usual rules of classic Sudoku apply to each grid of the 9 by 9 game. The player's task is to arrange the numbers from 1 to 9 in each empty cell. Each row, column and 3 by 3 box must not contain identical numbers.
The uniqueness of the Samurai Sudoku puzzle is this: each of these five tables cannot be solved individually, there is only a single solution for all of them.
- Windoku
In this variation of Sudoku, there are additional blocks within the grid that are highlighted in color. These extra four cells are called “Windows”.
These boxes overlap with the standard rows, columns and cells of 3 by 3 sudoku, making the puzzle more challenging. In classic Sudoku, every row, every column and every 3 by 3 box must contain numbers from 1 to 9 without repeats. And in Windoku, along with these rules comes an additional one - all four windows must also contain numbers from 1 to 9 without repeats.
- More or Less Sudoku
Another modification of the classic sudoku. In this puzzle, the grid does not contain pre-filled digits in the task. Instead, the cells have comparison signs “>” and “<”. They show how the digits in the neighboring cells of the game table should relate to each other.
- Sudoku Asterisk
In the grid there is an additional, highlighted area. It consists of 9 cells and is shaped like an asterisk. Asterisk is a typographical sign in the form of an asterisk (*). In the cells of this game you also need to put the numbers from 1 to 9 according to the classical rules of Sudoku.
