What is the smallest solvable Sudoku?

An ordinary puzzle with a unique solution must have at least 17 clues, but this is not mathematically proven. There is a solvable puzzle with at most 21 clues for every solved grid, with the largest minimal puzzle found so far has 40 clues in the 81 cells. Similar results are known for variants and smaller grids.

What is the shortest Sudoku Solver?

The shortest Java Sudoku solver is 258 bytes. Contributors: David Singleton created the algorithm and did the initial reduction work. Mick Killianey and David Beaumont reduced it to 299 bytes.

Are there unsolvable Sudoku puzzles?

Realistically, no! There are 6,670,903,752,021,072,936,960 possible solvable Sudoku grids that yield a unique result (that's 6 sextillion, 670 quintillion, 903 quadrillion, 752 trillion, 21 billion, 72 million, 936 thousand, 960 in case you were wondering). That's way more than the number of stars in the universe.

What is the shortest Sudoku time?

A Sudoku Master from China Wang Shiyao solved 9x9 sudoku grid in 54.44 seconds at the World Sudoku & Puzzle Championship held in Prague. However...

How many possible 9x9 Sudoku grids are there?

They discovered that the number of possible 9 by 9 Sudoku grids is N=6670903752021072936960 which is approximately 6.671×10²¹.

17 Givens - The Sudoku Minimum - How Hard To Solve?

Can a 9 * 9 Sudoku have multiple solutions?

Sudoku is a number puzzle consisting of a 9 x 9 grid in which some cells contain clues in the form of digits from 1 to 9. The solver's jobs is to fill in the remaining cells so that each row, column and 3×3 box in the grid contains all nine digits. There's another unwritten rule: the puzzle must have only one solution.

Is there 16 square Sudoku?

Hexadecimal Sudokus (also known as 16x16 Sudoku) are a larger version of regular Sudoku that feature a 16 x 16 grid, and 16 hexadecimal digits. Each row, column and 4x4 block contains all the digits 0 thru F (or numbers from 1 to 16, in the decimal versions).

What is the 159 rule in Sudoku?

Normal sudoku rules apply: Each row, column, and region indicated by thick borders in the grid must contain the digits 1 to 9 once each. 159: Digits in column 1 indicate the column in which the digit 1 appears in that row (e.g. if r4c1 is a 6, r4c6 is a 1).

Is there 16 * 16 Sudoku?

16 x 16 sudoku puzzles work just the same as regular 9 x 9 sudoku puzzles, but they are, well, a lot bigger! Infact whereas a normal sudoku has 81 squares in it, a 16x16 sudoku has 256 squares in it, so you get a lot more puzzle for your money.

What is the average time someone solved a Sudoku?

It is believed that the average Sudoku player spends approximately 20 minutes solving a typical Sudoku puzzle. For very hard puzzles, that number can be much higher. While the game itself can be challenging and complex, several strategies can be used successfully to find the solution.

What is not allowed in Sudoku?

You can use only numbers from 1 to 9. Each 3×3 block can only contain numbers from 1 to 9. Each vertical column can only contain numbers from 1 to 9. Each horizontal row can only contain numbers from 1 to 9.

Is Sudoku just guessing?

Sudoku does not require guessing. In fact, when solving Sudoku puzzles, you're better off NOT guessing at all. Sudoku is a logic puzzle, using the power of simple deductive reasoning and process of elimination to fill in the gaps in the grid. Simply put – you don't need luck to play Sudoku.

What is an evil Sudoku puzzle?

What is Sudoku Evil? Sudoku evil is a 9×9 grid sudoku puzzle with the highest possible level of difficulty. It's an advanced level only for experienced sudoku solvers.

Can 1 Sudoku have multiple solutions?

A well-formed Sudoku puzzle is one that has a unique solution. A Sudoku puzzle can have more than one solution, but in this case the kind of logical reasoning we described while discussing solving strategies may fall short. There are examples of rank-3 Sudoku puzzles with 17 givens that are well-formed.

Is 6 minutes good for Sudoku?

5 minutes is more than enough time to jump start your brain, re-evaluate your Sudoku strategy, and develop a new perspective on how to view the Sudoku grid. So “take 5” and give yourself a new chance at solving Sudoku puzzles!

What is the hardest Sudoku game?

Expert Sudoku is a game for experienced Sudoku players with a very high level of difficulty. This hardest Sudoku puzzle is characterized by the fact that only a few numbers are shown in the Sudoku square, which consists of 9 small squares, where the cells are located 3x3.

What is Sudoku rule of 1?

Rule 1 - Each row must contain the numbers from 1 to 9, without repetitions. The player must focus on filling each row of the grid while ensuring there are no duplicated numbers. The placement order of the digits is irrelevant. Every puzzle, regardless of the difficulty level, begins with allocated numbers on the grid.

What is the rule of 3 Sudoku?

If three candidates can be found in only the same three Cells of a region (Row, Column or Square), then one of these candidates is the solution for the first of these Cells, a second one is the solution for the second Cell and the last candidate is the solution for the third Cell.

What is 9x9 Sudoku?

Sudoku is played on a grid of 9 x 9 spaces. Within the rows and columns are 9 “squares” (made up of 3 x 3 spaces). Each row, column and square (9 spaces each) needs to be filled out with the numbers 1-9, without repeating any numbers within the row, column or square.

What is the 45 rule in Sudoku?

The 45 rule is a basic solving-technique in Killer Sudoku. Each house (row, column, nonet) must add to 45 (the sum of the digits 1 through 9).

What is Sudoku 4 cell rule?

Rules of Quadruple Sudoku

The object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 (one number per cell) so that each row, each column, and each of the nine 3x3 boxes contains all the nine different numbers 1 through 9. The clues are in the form of sets of four special clue-numbers.

What is the magic number in Sudoku?

Now Gary McGuire, a mathematician at University College Dublin, has come up with what he says is a proof that finds the minimum number of clues, or starting digits, needed to complete the game is 17.

Is Sudoku always 3x3?

The game of Sudoku consists of a grid of nine rows and nine columns subdivided into nine 3x3 subgrids. It has two basic rules: Each column, each row, and each box (3x3 subgrid) must have the numbers 1 to 9. No column, row or box can have two squares with the same number.

What is the red dot in Sudoku?

The central column (in green) has only two spaces left, and they must contain a 2 and a 6. In the center-right square, there is a 6 (circled in red) which shows us that we can eliminate 6 as being in the top empty space of the column – so that space must contain 2 (marked in blue).

Is Sudoku 1 9?

Sudoku is defined by Merriam-Webster as a 9-by-9 grid puzzle in which the grid is divided into 3-by-3 boxes. Every row, column and box must contain the numbers one through nine, no repeats.