Sudoku Solving Algorithm

Question

I have tried writing the algorithm by referring this.
But i am getting Error of StackOverFlow.
Help me out to find what is wrong in the program? Is it the recursion part?

public void beginSolving(int board[][],int x,int y){
    int i = 1;
    if(unassignedCell(board,x,y)){
        board[x][y] = i;
        if(isValidCell(board,y,x,i)){
            board[x][y] = i;
        }
        if(!isValidCell(board,y,x,i)){
            board[x][y] = 0;
            i++;
        }
    } else { 
        while(x<9){
            beginSolving(board,x++,y);
            if(x==9){
                x = 1;
                beginSolving(board,x,y++);
                if(y==9){

                }
            }
        }
    }
}

Henry · Accepted Answer · 2014-06-01 06:37:09Z

3

Look at the recursive calls: beginSolving(board,x++,y). The x and y parameters are the same as in the original call (remember that the value of x++ is the value before it is incremented). Thus it is likely that you enter a never ending recursion.

The while(x < 9) will never terminate since whenever x reaches 9 it is reset to 1.

The algorithm never tries to set a number other than 1 into the board.

There may be other problems with the code as well, I did not check it in detail.

edited Jun 1, 2014 at 6:37

answered Jun 1, 2014 at 6:25

Henry

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3 Comments

votelessbubble Over a year ago

I am a complete beginner so if possible can you help me out with getting the solution. Should i make it ++x?

Henry Over a year ago

Yes, ++x is better.

ug_ Over a year ago

@MärmîkŠhâh StackOverflow errors are a great way to practice your debugging skills. You should set a breakpoint at the start of your method and run through your application and see how it works.

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