org.mariuszgromada.math.janetsudoku

Class SudokuSolver

java.lang.Object

org.mariuszgromada.math.janetsudoku.SudokuSolver

public class SudokuSolver
extends Object

Sudoku board, with predefined Sudoku examples and possibility to load external examples from arrays or files. Class implements loading methods as well as Sudoku solving methods.

Version:

1.1.1

Author:

Mariusz Gromada
mariuszgromada.org@gmail.com
Janet Sudoku - project web page
MathSpace.pl
MathParser.org - mXparser project page
Janet Sudoku on GitHub
Janet Sudoku on CodePlex
Janet Sudoku on SourceForge
Janet Sudoku on BitBucket
mXparser-MathParser.org on GitHub

Field Summary

Fields

Modifier and Type	Field and Description
static int	SOLUTION_NON_UNIQUE Solution exists and is non-unique.
static int	SOLUTION_NOT_EXISTS Solution does not exist.
static int	SOLUTION_UNIQUE Solution exists and is unique.
static int	SOLVING_STATE_NOT_STARTED Sudoku solving not initiated.
static int	SOLVING_STATE_SOLVED Sudoku solving finished and successful.
static int	SOLVING_STATE_STARTED Sudoku solving started.

Constructor Summary

Constructors

Constructor and Description
SudokuSolver() Default constructor - only board initialization.
SudokuSolver(ArrayList<String> boardDefinition) Constructor - based on file path to the Sudoku definition.
SudokuSolver(int exampleNumber) Constructor - based on the Sudoku predefined example number.
SudokuSolver(int[][] sudokuBoard) Constructor - based on array representing Sudoku board.
SudokuSolver(String filePath) Constructor - based on file path to the Sudoku definition.
SudokuSolver(String[] boardDefinition) Constructor - based on file path to the Sudoku definition.

Method Summary

Methods

Modifier and Type	Method and Description
String	boardAndEmptyCellsToString() Returns string board and empty cells representation.
String	boardToString() Returns string board (only) representation.
int	checkIfUniqueSolution() Method searching all solutions procedure.
void	clearMessages() Clears list of recorded messages.
void	clearPuzzels() To clear the Sudoku board.
void	disableRndSeedOnEmptyCells() By default random seed on empty cells is enabled.
void	disableRndSeedOnFreeDigits() By default random seed on free digits is enabled.
String	emptyCellsToString() Returns string empty cells (only) representation.
void	enableRndSeedOnEmptyCells() By default random seed on empty cells is enabled.
void	enableRndSeedOnFreeDigits() By default random seed on free digits is enabled.
int	findAllSolutions() Method searching all solutions procedure.
BoardCell[]	getAllBoardCells() Get all current board cells.
ArrayList<SudokuBoard>	getAllSolutionsList() Gets all solutions list evaluated by the findAllSolutions() method
int[][]	getBoard() Gets array representing Sudoku board.
int[][]	getBoardCopy() Method for copy current board content
int	getBoardState() Return current Sudou board state.
int	getCellDigit(int rowIndex, int colIndex) Returns cell digit from current Sudoku board.
int	getClosedRoutesNumber() Number of routes that were assessed, but lead to nothing and required step back.
double	getComputingTime() Return solving time in seconds..
int[][]	getEmptyCells() Gets array representing evaluated empty cells.
String	getLastErrorMessage() Gets last recorded error message.
String	getLastMessage() Gets last recorded message.
String	getMessages() Returns list of recorded messages.
BoardCell[]	getSolutionBoardCells() Return solution board cells keeping the solution path order.
int[][]	getSolvedBoard() Gets array representing solved Sudoku board.
int	getSolvingState() Return current solving status.
int	loadBoard(ArrayList<String> boardDefinition) Loads Sudoku from array of strings.
int	loadBoard(int exampleNumber) Loads Sudoku example given by the parameter exampleNumber.
int	loadBoard(int[][] sudokuBoard) Loads Sudoku from array.
int	loadBoard(String filePath) Loads Sudoku from file.
int	loadBoard(String[] boardDefinition) Loads Sudoku from array of strings.
boolean	saveBoard(String filePath) Saves board to the text file.
boolean	saveBoard(String filePath, String headComment) Saves board to the text file.
boolean	saveBoard(String filePath, String headComment, String tailComment) Saves board to the text file.
boolean	saveSolvedBoard(String filePath) Saves solved board to the text file.
boolean	saveSolvedBoard(String filePath, String headComment) Saves solved board to the text file.
boolean	saveSolvedBoard(String filePath, String headComment, String tailComment) Saves solved board to the text file.
int	setCell(int rowIndex, int colIndex, int digit) Manually set cell value.
String	solutionPathToString() Return string representation of cells that lead to the solution, keeping the sequence.
int	solve() Method starts solving procedure.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SOLVING_STATE_NOT_STARTED

public static final int SOLVING_STATE_NOT_STARTED

Sudoku solving not initiated.

See Also:

Constant Field Values

SOLVING_STATE_STARTED

public static final int SOLVING_STATE_STARTED

Sudoku solving started.

See Also:

Constant Field Values

SOLVING_STATE_SOLVED

public static final int SOLVING_STATE_SOLVED

Sudoku solving finished and successful.

See Also:

Constant Field Values

SOLUTION_NOT_EXISTS

public static final int SOLUTION_NOT_EXISTS

Solution does not exist.

See Also:

checkIfUniqueSolution(), Constant Field Values

SOLUTION_UNIQUE

public static final int SOLUTION_UNIQUE

Solution exists and is unique.

See Also:

checkIfUniqueSolution(), Constant Field Values

SOLUTION_NON_UNIQUE

public static final int SOLUTION_NON_UNIQUE

Solution exists and is non-unique.

See Also:

checkIfUniqueSolution(), Constant Field Values

Constructor Detail

SudokuSolver

public SudokuSolver()

Default constructor - only board initialization.

SudokuSolver

public SudokuSolver(int exampleNumber)

Constructor - based on the Sudoku predefined example number.

Parameters:

exampleNumber - number of Sudoku example to load between 1 and SudokuPuzzles.NUMBER_OF_PUZZLE_EXAMPLES

SudokuSolver

public SudokuSolver(String filePath)

Constructor - based on file path to the Sudoku definition.

Parameters:

filePath - Path to the sudoku definition.

SudokuSolver

public SudokuSolver(String[] boardDefinition)

Constructor - based on file path to the Sudoku definition.

Parameters:

boardDefinition - Board definition (as array of strings, each array entry as separate row).

SudokuSolver

public SudokuSolver(ArrayList<String> boardDefinition)

Constructor - based on file path to the Sudoku definition.

Parameters:

boardDefinition - Board definition (as list of strings, each list entry as separate row).

SudokuSolver

public SudokuSolver(int[][] sudokuBoard)

Constructor - based on array representing Sudoku board.

Parameters:

sudokuBoard - 9x9 array representing Sudoku board/

Method Detail

loadBoard

public int loadBoard(int exampleNumber)

Loads Sudoku example given by the parameter exampleNumber.

Parameters:

exampleNumber - Number of predefined Sudoku example.

Returns:

ErrorCodes.SUDOKUSOLVER_LOADBOARD_LOADING_FAILED or SudokuBoard.BOARD_STATE_LOADED.

loadBoard

public int loadBoard(String filePath)

Loads Sudoku from file.

Parameters:

filePath - File path that contains board definition.

Returns:

ErrorCodes.SUDOKUSOLVER_LOADBOARD_LOADING_FAILED or SudokuBoard.BOARD_STATE_LOADED.

loadBoard

public int loadBoard(String[] boardDefinition)

Loads Sudoku from array of strings.

Parameters:

boardDefinition - Board definition as array of strings (each array entry as separate row).

Returns:

ErrorCodes.SUDOKUSOLVER_LOADBOARD_LOADING_FAILED or SudokuBoard.BOARD_STATE_LOADED.

loadBoard

public int loadBoard(ArrayList<String> boardDefinition)

Loads Sudoku from array of strings.

Parameters:

boardDefinition - Board definition as list of strings (each list entry as separate row).

Returns:

ErrorCodes.SUDOKUSOLVER_LOADBOARD_LOADING_FAILED or SudokuBoard.BOARD_STATE_LOADED.

loadBoard

public int loadBoard(int[][] sudokuBoard)

Loads Sudoku from array.

Parameters:

sudokuBoard - Array representing Sudoku puzzles.

Returns:

ErrorCodes.SUDOKUSOLVER_LOADBOARD_LOADING_FAILED or SudokuBoard.BOARD_STATE_LOADED.

saveBoard

public boolean saveBoard(String filePath)

Saves board to the text file.

Parameters:

filePath - Path to the file.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String), SudokuStore.boardToString(int[][])

saveBoard

public boolean saveBoard(String filePath,
                String headComment)

Saves board to the text file.

Parameters:

filePath - Path to the file.

headComment - Comment to be added at the head.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String, String), SudokuStore.boardToString(int[][], String)

saveBoard

public boolean saveBoard(String filePath,
                String headComment,
                String tailComment)

Saves board to the text file.

Parameters:

filePath - Path to the file.

headComment - Comment to be added at the head.

tailComment - Comment to be added at the tail.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String, String, String), SudokuStore.boardToString(int[][], String, String)

saveSolvedBoard

public boolean saveSolvedBoard(String filePath)

Saves solved board to the text file.

Parameters:

filePath - Path to the file.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String), SudokuStore.boardToString(int[][])

saveSolvedBoard

public boolean saveSolvedBoard(String filePath,
                      String headComment)

Saves solved board to the text file.

Parameters:

filePath - Path to the file.

headComment - Comment to be added at the head.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String, String), SudokuStore.boardToString(int[][], String)

saveSolvedBoard

public boolean saveSolvedBoard(String filePath,
                      String headComment,
                      String tailComment)

Saves solved board to the text file.

Parameters:

filePath - Path to the file.

headComment - Comment to be added at the head.

tailComment - Comment to be added at the tail.

Returns:

True if saving was successful, otherwise false.

See Also:

SudokuStore.saveBoard(int[][], String, String, String), SudokuStore.boardToString(int[][], String, String)

setCell

public int setCell(int rowIndex,
          int colIndex,
          int digit)

Manually set cell value.

Parameters:

rowIndex - Cell row index between 0 and 8.

colIndex - Cell column index between 0 and 8.

digit - Cell digit between 1 and 9, or EMPTY_CELL.

Returns:

Number of empty cells that left if cell definition correct, ErrorCodes.SUDOKUSOLVER_SETCELL_INCORRECT_DEFINITION otherwise.

getCellDigit

public int getCellDigit(int rowIndex,
               int colIndex)

Returns cell digit from current Sudoku board.

Parameters:

rowIndex - Cell row index between 0 and 8.

colIndex - Cell column index between 0 and 8.

Returns:

Cell digit between 1 and 9, if cell empty then BoardCell.EMPTY. If indexes are out of range then error ErrorCodes.SUDOKUSOLVER_GETCELLDIGIT_INCORRECT_INDEX is returned.

solve

public int solve()

Method starts solving procedure.

Returns:

if board state is SudokuBoard.BOARD_STATE_EMPTY then ErrorCodes.SUDOKUSOLVER_SOLVE_SOLVING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_ERROR then ErrorCodes.SUDOKUSOLVER_SOLVE_SOLVING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_LOADED then ErrorCodes.SUDOKUSOLVER_SOLVE_SOLVING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_READY then returns solving status: SOLVING_STATE_SOLVED, ErrorCodes.SUDOKUSOLVER_SOLVE_SOLVING_FAILED.

findAllSolutions

public int findAllSolutions()

Method searching all solutions procedure.

Returns:

if board state is SudokuBoard.BOARD_STATE_EMPTY then ErrorCodes.SUDOKUSOLVER_FINDALLSOLUTIONS_SEARCHING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_ERROR then ErrorCodes.SUDOKUSOLVER_FINDALLSOLUTIONS_SEARCHING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_LOADED then ErrorCodes.SUDOKUSOLVER_FINDALLSOLUTIONS_SEARCHING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_READY then returns number of all solutions found.

checkIfUniqueSolution

public int checkIfUniqueSolution()

Method searching all solutions procedure.

Returns:

if board state is SudokuBoard.BOARD_STATE_EMPTY then ErrorCodes.SUDOKUSOLVER_CHECKIFUNIQUESOLUTION_CHECKING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_ERROR then ErrorCodes.SUDOKUSOLVER_CHECKIFUNIQUESOLUTION_CHECKING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_LOADED then ErrorCodes.SUDOKUSOLVER_CHECKIFUNIQUESOLUTION_CHECKING_NOT_STARTED, if board state is SudokuBoard.BOARD_STATE_READY then returns SOLUTION_UNIQUE, SOLUTION_NON_UNIQUE, SOLUTION_NOT_EXISTS.

clearPuzzels

public void clearPuzzels()

To clear the Sudoku board.

getMessages

public String getMessages()

Returns list of recorded messages.

Returns:

List of recorded messages.

clearMessages

public void clearMessages()

Clears list of recorded messages.

getLastMessage

public String getLastMessage()

Gets last recorded message.

Returns:

Last recorded message.

getLastErrorMessage

public String getLastErrorMessage()

Gets last recorded error message.

Returns:

Last recorded message.

getBoardState

public int getBoardState()

Return current Sudou board state.

Returns:

SudokuBoard.BOARD_STATE_READY or SudokuBoard.BOARD_STATE_EMPTY or SudokuBoard.BOARD_STATE_ERROR.

getBoardCopy

public int[][] getBoardCopy()

Method for copy current board content

Returns:

Current copy of Sudoku board

getSolvingState

public int getSolvingState()

Return current solving status.

Returns:

SOLVING_STATE_NOT_STARTED or ErrorCodes.SUDOKUSOLVER_SOLVE_SOLVING_FAILED or SOLVING_STATE_SOLVED.

getBoard

public int[][] getBoard()

Gets array representing Sudoku board.

Returns:

Array representing Sudoku board.

getSolvedBoard

public int[][] getSolvedBoard()

Gets array representing solved Sudoku board.

Returns:

Array representing solved Sudoku board.

getAllSolutionsList

public ArrayList<SudokuBoard> getAllSolutionsList()

Gets all solutions list evaluated by the findAllSolutions() method

Returns:

List of all found solutions

See Also:

findAllSolutions()

getEmptyCells

public int[][] getEmptyCells()

Gets array representing evaluated empty cells. meaning number of still free digits possible.

Returns:

Array representing evaluated empty cells.

getAllBoardCells

public BoardCell[] getAllBoardCells()

Get all current board cells.

Returns:

Array of current board cells.

getSolutionBoardCells

public BoardCell[] getSolutionBoardCells()

Return solution board cells keeping the solution path order. If error was encountered while solving path to the solution will be incomplete, but will show where solving process was aborted.

Returns:

Array of board cells that lead to the solution (keeping the path order).

getComputingTime

public double getComputingTime()

Return solving time in seconds..

Returns:

Solvnig time in seconds.

getClosedRoutesNumber

public int getClosedRoutesNumber()

Number of routes that were assessed, but lead to nothing and required step back. The higher number to more computation was performed while solving.

Returns:

Number of closed routes while solving.

enableRndSeedOnEmptyCells

public void enableRndSeedOnEmptyCells()

By default random seed on empty cells is enabled. This parameter affects solving process only. Random seed on empty cells causes randomization on empty cells within empty cells with the same number of still free digits. Enabling extends ability to find different solutions, if exists.

disableRndSeedOnEmptyCells

public void disableRndSeedOnEmptyCells()

By default random seed on empty cells is enabled. This parameter affects solving process only. Random seed on empty cells causes randomization on empty cells within empty cells with the same number of still free digits. Disabling limits ability to find different solutions, if exists.

enableRndSeedOnFreeDigits

public void enableRndSeedOnFreeDigits()

By default random seed on free digits is enabled. This parameter affects solving process only. Random seed on free digits causes randomization on accessing free digits for a given empty cells. Each free digits is a starting point for a new recursive sub-path potentially leading to solution. Enabling extends ability to find different solutions, if exists.

disableRndSeedOnFreeDigits

public void disableRndSeedOnFreeDigits()

By default random seed on free digits is enabled. This parameter affects solving process only. Random seed on free digits causes randomization on accessing free digits for a given empty cells. Each free digits is a starting point for a new recursive sub-path potentially leading to solution. Disabling limits ability to find different solutions, if exists.

boardAndEmptyCellsToString

public String boardAndEmptyCellsToString()

Returns string board and empty cells representation.

Returns:

Board and empty cells representation.

boardToString

public String boardToString()

Returns string board (only) representation.

Returns:

Board (only) representation.

emptyCellsToString

public String emptyCellsToString()

Returns string empty cells (only) representation.

Returns:

Empty cells (only) representation.

solutionPathToString

public String solutionPathToString()

Return string representation of cells that lead to the solution, keeping the sequence.

Returns:

String representation of entries that lead to the solution.