我正在制作一个数独游戏程序，并且我'创建'一个递归算法来解决数独游戏。问题是，有时候它会在瞬间完美地工作，有时会卡住并且工作10秒钟，有时候我只需要退出它。 可能导致这种情况的任何想法？
我保留了代码原样，因为我不确定你是如何回答这个问题的（如果你复制并试一试或只是检查逻辑）。如果你愿意，我可以写出片段。
谢谢！
import java.util.Random;
/**
* @Program Sudoku
*
* @date November 2013
* @hardware MacBook Pro 17", mid 2010, i7, 8GiB RAM
* @IDE eclipse SDK 4.3.1
* @purpose generates a valid 9x9 sudoku grid
*
*/
public class SudokuSolver //seems to werk !!
{
//create a validitychecker object(will be used as Sudoku.isValid();)
validityChecker Sudoku = new validityChecker();
//Create a 2D array where the full sudoku grid will be stored
private int[][] grid = new int[9][9];
//Creates a 2D array for the playable sudoku grid (with elements removed)
private int[][] playingGrid = new int[9][9];
private Random Ran = new Random();
/**
* @purpose use this construct if you wish to generate a new sudoku
* @param difficultyLevel removes amount of elements from sudoku using the equation elementToRemove=40+15*difficultyLevel
*/
SudokuSolver(int difficultyLevel)
{
//generate an empty grid
generateBaseGrid();
//populate it with a valid sudoku
solveSudoku(0,0);
//store this in a new from which elements shall be removed
for(int i = 0; i < grid.length; i++)
playingGrid[i] = grid[i].clone();
//calculate the amount of elements to be removed
int difficultyMultiplier = 15;
int baseDifficulty = 40;
int difficulty = baseDifficulty+difficultyLevel*difficultyMultiplier;
//and remove them
removeElements(difficulty);
}
/**
* @purpose use this constructor if you just want to use methods and solve
* @param the sudoku you wish to solve. values have to be within the range 1-9(inclusive), and -1 for unknown
* @note to get the solved sudoku use the fullGrid getter.
*/
SudokuSolver(int[][] pg)
{
//lets clone out the arrays - we don't want to just have references ...
for(int i = 0; i < pg.length; i++)
grid[i] = pg[i].clone();
for(int i = 0; i < grid.length; i++)
playingGrid[i] = grid[i].clone();
int coords[] = findOnes(grid);
solveSudoku(coords[0],coords[1]);
System.out.println(coords[0]+" "+coords[1]);
}
/**
* Use this if you only wish to use the internal methods
*/
SudokuSolver()
{}
//this method was implemented later, and I'm too lazy to change methods that use the procedure, but don't call the method. Maybe in next version
/**
* @purpose creates a copy of the passed array
* @param the array you wish to be copied
* @return returns a clone of the passed 2D array
*/
public int[][] cloneBoard(int[][] sudokuArray)
{
int[][] result = new int[9][9];
for(int i = 0; i < sudokuArray.length; i++)
result[i] = sudokuArray[i].clone();
return result;
}
/*
*@purpose fills the grid with -1s; This is for proper functionality during validation
*/
private void generateBaseGrid()
{
//iterates through all the values and stores -1s in it
for(int r=0;r<9;r++)
for(int c=0;c<9;c++)
grid[r][c] = -1;
//System.out.println("Base Grid Created");
}
/**
* @purpose checks if there are -1s in the grid, if so the grid is playable (its not a solution)
* @return true if its playable
*/
public boolean isGridPlayable()
{
for(int i=0;i<9;i++)
for(int j=0;j<9;j++)
if(grid[i][j]==-1)
return true;
return false;
}
/**
*
* @return the generated grid with all elements (for one without some elements use theGrid()) for generator
* @return the solved grid for solver
*/
public int[][] fullGrid()
{
return grid;
}
/**
* @purpose returns the playing grid
* @return the playable grid
*/
public int[][] theGrid()
{
return playingGrid;
}
/*
* @purpose removes "amnt" of elements from the playingGrid
* @return whether the current method was successful
* @param the amount of elements to be removed
*/
private boolean removeElements(int amnt)
{
if(amnt==0) //yay base case
return true;
for(int i=0; i<20;i++)
{
int r=Ran.nextInt(9);
int c=Ran.nextInt(9);
int element=playingGrid[r][c];
if(element!=-1)
{
playingGrid[r][c]=-1;
if(removeElements(amnt-1))
{return true;}
}else{playingGrid[r][c]=element;//removed as per suggestioni--;}
}
}
return false;
}
//--------------Debugging--------------------------------
public void printUserGrid(int[][] printie)
{
for(int i=0;i<9;i++)
{
for(int j=0;j<9;j++)
{
int x = printie[i][j];
String bexp = Integer.toString(x);
if(x==-1)
bexp="[]";
else bexp+=" ";
System.out.print(bexp+" ");
if(j==2||j==5)
System.out.print(" ");
}
System.out.println();
if(i==2||i==5)
System.out.println();
}
}
// //----------Main only for debugging-----------------------
public static void main(String[] args)
{
SudokuSolver Generator = new SudokuSolver(2);
int[][] generatedGrid = Generator.theGrid();
int[][] fullGrid = Generator.fullGrid();
Generator.printUserGrid(fullGrid);
// Generator.printUserGrid(generatedGrid);
System.out.println("\n\n");
SudokuSolver Solver = new SudokuSolver(generatedGrid);
Solver.printUserGrid(fullGrid);
}
}
编辑： 我忘记提到的一个关键问题是solveSudoku方法，它重新排列了一些值。这意味着如果我从** 3开始它没有问题返回312（这只是一个例子）。所以我假设那里某处有一些严重的逻辑错误。
答案 0 :(得分：0)
您尝试解决的问题是Artificial Intelligence问题。按brute-force或更好地称为普通backtracking实际上意味着您可能具有指数时间复杂度。
指数解决方案预计需要很长时间。在order of guesswork与实际解决方案匹配的某些情况下，您的求解器将返回更快的结果。
所以你能做什么：
Constraint Satisfaction的AI技术，并尝试实现它。答案 1 :(得分：-1)
这是我的SudokuSolver版本：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Sudoku
{
//This member has been intentionally left public, as the solved sudoku is
//obtained from here and user will find it much easier to handle this.
//The Sudoku input has to be given through this instance variable only.
//Moreover, many a times, Sudoku inputs as an edit-able 2D array is more
//comfortable than passing a whole 9x9 2D array as a constructor parameter.
public String SUDOKU[][]=new String[9][9];
//This variable records the nature of the Sudoku whether solvable or not
public boolean VALID=true;
public Sudoku()//this constructor can be used to create SUDOKU objects
{
for(int i=0;i<9;i++)
for(int j=0;j<9;j++)
SUDOKU[i][j]="";
}
private Sudoku(String SDK[][])//This is constructor kept private for program use
{
SUDOKU=SDK;
}
//This function checks if a certain digit is possible in a particular cell
private boolean isPossible(int n,int i,int j)
{
for(int a=i/3*3;a<i/3*3+3;a++)
for(int b=j/3*3;b<j/3*3+3;b++)
if(SUDOKU[a][b].length()==1 && n==Integer.parseInt(SUDOKU[a][b]))
return false;
for(int k=0;k<9;k++)
if(SUDOKU[i][k].length()==1 && n==Integer.parseInt(SUDOKU[i][k]) || SUDOKU[k][j].length()==1 && n==Integer.parseInt(SUDOKU[k][j]))
return false;
return true;
}
//The following function is compulsory as it is the only function to place appropriate
//possible digits in the cells of the Sudoku. The easiest Sudokus will get solved here.
private void fillPossibles()
{
boolean newdigit=false;
for(int i=0;i<9;i++)
for(int j=0;j<9;j++)
if(SUDOKU[i][j].length()!=1)
{
SUDOKU[i][j]="";
int count=0;
for(int k=1;k<10;k++)
if(isPossible(k,i,j))
{
SUDOKU[i][j]+=k;
count++;
}
if(count==1)
newdigit=true;
}
if(newdigit)
fillPossibles();
}
//This following function is optional, if the Sudoku is known to be genuine. As,
//in that case it only increases the solving speed!! But if the nature is not known,
//this function becomes necessary because the nature of the Sudoku is checked here.
//It returns true if any cell is filled with a digit and false for all other cases
private boolean deepFillPossibles(int ai,int aj,int bi,int bj,boolean first)
{
if(SUDOKU!=null)
for(char c='1';c<='9';c++)
{
int count=0,digit=0,possibility=0,i=0,j=0;
boolean valid=true;
for(int a=ai;a<bi;a++)
for(int b=aj;b<bj;b++)
{
if(SUDOKU[a][b].length()==0)
valid=false;
for(int k=0;k<SUDOKU[a][b].length();k++)
if(SUDOKU[a][b].charAt(k)==c)
{
if(SUDOKU[a][b].length()>1)
{
i=a; j=b; count++;
}
if(SUDOKU[a][b].length()==1)
digit++;
possibility++;
}
}
//the following code is executed only if solution() is called first time
if(first && (digit>1 || valid && possibility==0))
{
SUDOKU=null; return false;
}
if(count==1)
{
SUDOKU[i][j]=String.valueOf(c);
fillPossibles(); return true;
}
}
return false;
}
//This function is also optional if Sudoku is genuine. It only combines the solving
//power of fillPossibles() and deepFillPossibles() to reduce memory consumption
//in the next stages. In many cases the Sudoku gets solved at this stage itself.
private void solution(boolean first)
{
fillPossibles();
for(int i=0;i<9;i++)
if(deepFillPossibles(i,0,i+1,9,first) || deepFillPossibles(0,i,9,i+1,first) ||
deepFillPossibles(i/3*3,i%3*3,i/3*3+3,i%3*3+3,first))
i=-1;
}
//This function is the most challenging. No Sudoku can ever escape solution after
//passing this stage. It uses ECHO TREE logic implementing brute force to check all
//kinds of combinations until solution is obtained. It returns a null for no solution.
private void treeSolution(Tracker track)
{
if(SUDOKU==null)
{
track.TRACK_SUDOKU=null;
return;
}
solution(false);
//For a genuine sudoku the statement could have been replaced by "fillPossibles();"
//(Only it would make solving slower and increase memory consumption!)
//But it is risky if there is a doubt regarding the genuineness of the Sudoku
int a=-1,b=-1;
for(int i=0;i<9;i++)
for(int j=0;j<9;j++)
if(SUDOKU[i][j].length()>1 && a==-1)
{
a=i; b=j;
}
else if(SUDOKU[i][j].length()==0)
return;
if(a==-1)//checks if the Sudoku is solved or not setting necessary flags
{
track.TRACK_SOLUTION++;
for(int i=0;i<9;i++)
for(int j=0;j<9;track.TRACK_SUDOKU[i][j]=SUDOKU[i][j],j++);
return;
}
String temp[][]=new String[9][9];
for(int k=0;k<SUDOKU[a][b].length();k++)
{
for(int i=0;i<9;i++)
for(int j=0;j<9;temp[i][j]=SUDOKU[i][j],j++);
temp[a][b]=String.valueOf(SUDOKU[a][b].charAt(k));
new Sudoku(temp).treeSolution(track);
//The following condition stops the braching TREE if the Sudoku is solved by
//echoing back to the root, depending on the flags set on being solved
if(track.TRACK_SOLUTION==2 || track.TRACK_SUDOKU==null)
return;
}
return;
}
//This is the last function which has public access and can be called by the user.
//It sets the Sudoku as null if non-genuine and VALIDity as false if no unique solution
public void solve()
{
try
{
for(int i=0;i<9;SUDOKU[i][8]=SUDOKU[i][8],SUDOKU[8][i]=SUDOKU[8][i],i++);
}
catch(Exception e)
{
SUDOKU=null; VALID=false; return;
}
Tracker track=new Tracker();
solution(true);
treeSolution(track);
SUDOKU=track.TRACK_SOLUTION==0?null:track.TRACK_SUDOKU;
if(track.TRACK_SOLUTION!=1)
VALID=false;
}
}
//the following class is purposely designed to easily track the changes during solution,
//including the nature of the Sudoku and the solution of the Sudoku(if possible)
class Tracker
{
protected int TRACK_SOLUTION=0;
protected String TRACK_SUDOKU[][]=new String[9][9];
}
public class SudokuSolver extends JApplet implements KeyListener, MouseListener
{
private String SUDOKU[][]=new String[9][9];
private Sudoku SDK=new Sudoku();
private Image BOX[][]=new Image[9][9],SELECT_IMG;//BOX is an array of square images
private int SELECT_ROW=4,SELECT_COLUMN=4;//stores the position of the selection box
//this function is used to initialize the coloured square images and fonts
public void init()
{
resize(190,190);
setFont(new Font("Dialog",Font.BOLD,12));
addMouseListener(this);
addKeyListener(this);
Graphics g;
for(int i=0;i<9;i++)
for(int j=0;j<9;SUDOKU[i][j]="",j++)
{
BOX[i][j]=createImage(22,22);
g=BOX[i][j].getGraphics();
if((i/3+j/3)%2==0)
g.setColor(Color.yellow);
else
g.setColor(Color.green);
g.fillRect(0,0,21,21);
g.setColor(Color.black);
g.drawRect(0,0,21,21);
}
//the following statements colour the selection box red
SELECT_IMG=createImage(22,22);
g=SELECT_IMG.getGraphics();
g.setColor(Color.red);
g.fillRect(0,0,21,21);
g.setColor(Color.black);
g.drawRect(0,0,21,21);
}
public void mouseExited(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseReleased(MouseEvent e){}
public void mouseClicked(MouseEvent e){}
//the following function handles the mouse click operations
public void mousePressed(MouseEvent e)
{
if(SDK.SUDOKU==null)
{
SDK.SUDOKU=new String[9][9];
for(int i=0;i<9;i++)
for(int j=0;j<9;SUDOKU[i][j]="",SDK.SUDOKU[i][j]="",j++);
SDK.VALID=true;
}
if(e.getY()<190 && e.getX()<190 && e.getY()%21!=0 && e.getX()%21!=0)
{
SELECT_ROW=e.getY()/21;
SELECT_COLUMN=e.getX()/21;
}
repaint();
}
public void keyReleased(KeyEvent e){}
//this function manages the operations associated with the various keys
public void keyPressed(KeyEvent e)
{
int code=e.getKeyCode();
if(code==KeyEvent.VK_DELETE || code==KeyEvent.VK_BACK_SPACE || code==KeyEvent.VK_SPACE)
{
SUDOKU[SELECT_ROW][SELECT_COLUMN]=""; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="";
}
switch(code)
{
case KeyEvent.VK_Y : if(SDK.SUDOKU!=null) SDK.VALID=true; break;
case KeyEvent.VK_UP : SELECT_ROW=(SELECT_ROW+8)%9; break;
case KeyEvent.VK_DOWN : SELECT_ROW=(SELECT_ROW+1)%9; break;
case KeyEvent.VK_LEFT : SELECT_COLUMN=(SELECT_COLUMN+8)%9; break;
case KeyEvent.VK_RIGHT : SELECT_COLUMN=(SELECT_COLUMN+1)%9; break;
case KeyEvent.VK_ENTER : SDK.solve(); break;
case KeyEvent.VK_N : if(SDK.SUDOKU!=null){ SDK.VALID=true; code=KeyEvent.VK_ESCAPE;}
case KeyEvent.VK_ESCAPE : if(SDK.SUDOKU==null)
{
SDK.SUDOKU=new String[9][9];
for(int i=0;i<9;i++)
for(int j=0;j<9;SUDOKU[i][j]="",SDK.SUDOKU[i][j]="",j++);
SDK.VALID=true;
}
else
for(int i=0;i<9;i++)
for(int j=0;j<9;SDK.SUDOKU[i][j]=SUDOKU[i][j],j++);
}
repaint();
}
//this function is for entering the numbers in the sudoku grid
public void keyTyped(KeyEvent e)
{
char code=e.getKeyChar();
if(Character.isDigit(code))
switch(code)
{
case '1': SUDOKU[SELECT_ROW][SELECT_COLUMN]="1"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="1"; break;
case '2': SUDOKU[SELECT_ROW][SELECT_COLUMN]="2"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="2"; break;
case '3': SUDOKU[SELECT_ROW][SELECT_COLUMN]="3"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="3"; break;
case '4': SUDOKU[SELECT_ROW][SELECT_COLUMN]="4"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="4"; break;
case '5': SUDOKU[SELECT_ROW][SELECT_COLUMN]="5"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="5"; break;
case '6': SUDOKU[SELECT_ROW][SELECT_COLUMN]="6"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="6"; break;
case '7': SUDOKU[SELECT_ROW][SELECT_COLUMN]="7"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="7"; break;
case '8': SUDOKU[SELECT_ROW][SELECT_COLUMN]="8"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="8"; break;
case '9': SUDOKU[SELECT_ROW][SELECT_COLUMN]="9"; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="9"; break;
default : SUDOKU[SELECT_ROW][SELECT_COLUMN]=""; SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN]="";
}
}
//the paint() function is designed to print the the sudoku grid and other messages
public void paint(Graphics g)
{
if(!SDK.VALID)
{
g.setColor(Color.white);
g.fillRect(1,1,188,188);
g.setColor(Color.black);
g.drawRect(0,0,189,189);
if(SDK.SUDOKU==null)
{
g.drawString("INVALID SUDOKU!!",45,80);
g.drawString("[PRESS ESCAPE TO RE-ENTER]",10,105);
}
else
{
g.drawString("INCOMPLETE SUDOKU!!",30,60);
g.drawString("Would you like to see a",30,90);
g.drawString("possible solution?",45,105);
g.drawString("Y / N",80,120);
}
}
else
{
for(int i=0;i<9;i++)
for(int j=0;j<9;j++)
{
g.drawImage(BOX[i][j],j*21,i*21,null);
g.drawString(SDK.SUDOKU[i][j],8+j*21,15+i*21);
}
g.drawImage(SELECT_IMG,SELECT_COLUMN*21,SELECT_ROW*21,null);
g.drawString(SDK.SUDOKU[SELECT_ROW][SELECT_COLUMN],8+SELECT_COLUMN*21,15+SELECT_ROW*21);
}
}
}
我试图尽可能使用最小蛮力