用JavaScript解决4x4（简化的）数独游戏

Question

I have a problem where I have to code an automatic solution to a given sudoku which is 4x4 which means the numbers go only as far 1 2 3 4. It's a simplified version of a sudoku since I am still new to programming.

I have a given template with random sudoku generated from it and I have to write a code to solve the sudoku automatically.
Here is what I have in the begining as sudoku that i have to solve

sudoku[6] = [[" ","2"," "," "],
             [" "," ","2"," "],
             [" "," "," ","3"],
             ["4"," "," "," "]

My idea was to insert "1234" into empty " " and then remove the numbers from "1234" when one of the numbers is already present in the column, row and quadrant. So what I wanted to do is with the use of loops go through all the positions in the tables and the moment I find for example "1" alone i will remove the 1 from "1234".

Here is the beggning of my code, it appears it doesnt work the moment I reach if, can you guys please tell me what I am doing wrong or why isn't it working when i get to my If. Thank you in advance.

var sudoku = sudoku[6];

// function to put "1234" into empty space ""
var concatenate = function (s)
{ 
   for (i=0; i<s.length; i++)
       for (j=0; j<s.length; j++)
            if (sudoku[i][j] === " ")
                sudoku[i][j] = "1234";
};

concatenate(sudoku);

// function to solve the sudoku automatically. 

var solve = function (t)
{ 
    for (i = 0; i<t.length; i++)
       for (j=0; j<t.length; j++)
           for (k=j; k<(4+j); k++)
                if (sudoku[i][j].length === 1)    // this is where it seems to bug, in this if im trying to find the position where we only have one number and not "1234"
                    var s = sudoku[i][j];
                if (sudoku[i][k-j] !== ("1" || "2" || "3" || "4"))  // here im finding the position of all position in the sudoku where ive got "1234" so i can remove the number found in the previous if.
                    {
                        var index = sudoku[i][k-j].indexOf(s);
                        var string_new = sudoku[i][k-j].substring(0,index) + sudoku[i][k-j].substring(index+1, 4);
                        sudoku[i][k-j] = string_new; 
                    }
};

Answer 1

There are known algorithms to solve the sudoku problem, you should take a look.

For such a small sudoku like yours, you may choose to implement not taking in account the computational time. (choose the simplest to implement)

For more infos: Sudoku solving algorithms

Reguarding your code, the idea (on paper) is not bad, but I really can't understand what you intended to do with that. For example:

if (sudoku[i][k-j] !== ("1" || "2" || "3" || "4"))

This line has no sense. The expression ("1" || "2" || "3" || "4") will always evaluates "1". So you are writing:

if (sudoku[i][k-j] !== "1")

Moreover sudoku[i][kj] is a string containing "1234" (or part of it), so you should use indexOf to check the presence of a character.

And what is the use of the internal for?

  for (k=j; k<(4+j); k++)

Why are you iterating from j to 4+j? You're always using kj to access the variable (sudoku[i][kj]), that is always between jj and 4+jj. So why don't:

  for (k=0; k<4; k++)

There are more other logic errors in you code... If you want to implement that idea, you should take your time to think what you are writing, or (better) use a known algorithm.

Answer 2

You should replace this one:

if (sudoku[i][k-j] !== ("1" || "2" || "3" || "4"))

to something like this:

if ( sudoku[i][k-j] !== "1" || sudoku[i][k-j] !== "2" || ...

or you can consider using a switch statement also, but I'm not sure if it's gonna solve the bug that you're struggling with that or not ...