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#Sudoku puzzle generator algorithm how to
#Sudoku puzzle generator algorithm full

There are some implementations out there in Python. Have you looked at existing algorithms and/or code?Ĭheck out for an algorithmic description, and Peter Norvig’s article at. Is there more elegant/efficient way to filling entire grid with numbers without breaking rules of placement and still random numbers? However, most of times, when I do not break any rules of placement a run to conflict – like empty cells where all candidates have been removed etc and I need to start over. This technique guarantees random grid without duplicate numbers.

Now for each row, cell and square corresponding to assigned cell I remove value of cell from these candidates, so each number is unique in a row/column/square.

Select random candidate from that cell and assign it as cell value.

#Sudoku puzzle generator algorithm full

When I am trying to generate full populated grid I am running into difficulties. I am right that second approach is better? Second approach is to create full valid grid with all 81 numbers and then remove until we are happy with number of remaining numbers and it is still solvable.įirst I used first approach but now I am going to use second because I think it is more effective (we are starting with valid puzzle which is guaranteed to be solvable).

There are two aproaches, start with blank grid and add numbers, then check if it is solvable.

But I am experiencing some problems I need help with. So now I am trying to write it again in optimal way. If(ntains(s)) unitsContainingS.I made an algorithm to generate sudokus, but it was terribly inefficient.

List> unitsContainingS = new ArrayList>() * map from all squares to the list of units the square is included in **Generates map from all squares to the list of units the square is included in Public static List cross(String a, String b) įor(int i = 0 i box = cross(boxHeight, boxWidth) * a list of strings comprised of all characters in a concatenated with all characters in b Its a native node.js extension written in C. **Returns cross product of two strings a and b As fast as possible sudoku solver and generator using the backtracking algorithm. Public static List> unitlist = getUnitList() In our next article we will tackle solving actual Sudoku Puzzles with GA's like the one shown in figure 2.

#Sudoku puzzle generator algorithm how to

This article demonstrates how to generate a fully populated Sudoku puzzle using a genetic algorithm. Public static List squares = cross(rows, cols) Sudoku is the latest fad for puzzle addicts and I suspect it's here to stay. Public static String digits = "123456789" Any thoughts on potential speedups? Is this just a bad way to generate sudoku?

The issue is that even if the solver finds one solution quickly it has to check all possible combinations to ensure uniqueness. The test for a unique solution is incredibly slow despite a fast solver that can solve puzzles with 'hard' or 'diabolical' rating in less than. This leaves a puzzle with a unique solution and the minimum number of squares possible. Repeat until all squares have been removed and tested. If the puzzle does not have a unique solution return the square to the puzzle. Test that the puzzle still has unique solution using a constrain propagation backtrack solver. This generates a random solved sudoku and works quite quickly. Start with an empty puzzle and the fill entire board with a backtrack solver that chooses numbers in a random order to try at each location. I am working on a sudoku puzzle generator that works as follows: