The fewest clues required for a proper Sudoku is 17, but not all completed grids can be reduced to a proper 17 clue Sudoku. About 49,000 unique (non-equivalent) Sudokus with 17 clues have been found.
Whats a hidden pair in Sudoku?
A hidden pair occurs when a pair of numbers appears in exactly two squares in a row, column, or block, but those two numbers aren’t the only ones in their squares. The 5 and 9 only occur in those two squares and nowhere else in the row, so those two squares can only contain 5 and 9 and no other numbers.
What is the trick to solve Sudoku?
There are more than a few techniques to solve a Sudoku puzzle, but per Conceptis Puzzles, the easiest way to a Sudoku solution is to, “Scan rows and columns within each triple-box area, eliminating numbers or squares and finding situations where only a single number can fit into a single square.” If you’re looking to …
Is there a strategy to solving Sudoku?
The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. One more complicated strategy is to look at pairs or triples of cells within a row, column, or block.
How is the number 4 determined in Sudoku?
Because they are the only occurences in the rows, all three columns can claim ‘3’. In the highlighted cells, ‘4’ occurs in only two cells in each of the two rows, and the cells belong to the same two columns. If one of the highlighted cells in one of two columns is ‘4’, the diagonal cell in another column must be ‘4’.
How many possible 9×9 Sudoku grids are there?
Sudoku is one of the most popular puzzle games of all time. The goal of Sudoku is to fill a 9×9 grid with numbers so that each row, column and 3×3 section contain all of the digits between 1 and 9. As a logic puzzle, Sudoku is also an excellent brain game.
When do you have more than one solution to a Sudoku puzzle?
If the number of clues is more than 20, most of the time it has only one solution (but no mathematical support is there). However, if the number of clues is less than 20 (for example: 12, 15, 17), multiple solutions may exist. This answer provides a grid with 77 digits and 2 solutions.
How are other candidate numbers eliminated in Sudoku?
So, other candidate numbers are esentially eliminated, making ‘1’ the only candidate. When the candidates for two cells in the same row/column/minigrid are the same two numbers, those two numbers can be eliminated from the candidate lists in other cells.
