sudoku_solver

sudoku_refined.c

#include <stdio.h>

#include <math.h>

#define N 9

#define unassigned 0
//int a[N][N];

//int numbers=0;

int i,j,k;                   //the loop arrays

int row=0,col=0;             //the row and col

int x=0,y=0;                 //the x and y coordinate





void output(int a[][N])

{

    for(row=0;row<N;row++)

    {

        for(col=0;col<N;col++)

        {

            printf("%d\t",a[row][col]);

        }

        printf("\n");

        printf("\n");

    }//end of for

}//end of output


int rowCheck(int a[][N],int row_value, int num)//corrected

{

    for(col=0;col<N;col++)

    {

            if(a[row_value][col]==num)

            {

                return 0; //cannot be done

            }


    }

    return 1; //is safe

}//


int colCheck(int a[][N],int col_value,int num)//corrected

{

     for(row=0;row<N;row++)

    {

        if(a[row][col_value]==num)

        {

                return 0; //cannot be done

        }

    }

    return 1; //is safe

}//


int boxCheck(int a[][N],int rowStart,int colStart, int num)//corrected

{

    for (row = 0; row < 3 ; row++)

        {


        for (int col = 0; col < 3; col++)

           {


                if (a[row+rowStart][col+colStart] == num)

                {

                    return 0; //not safe

                }

           }


        }

      return 1; //safe

}//


int isSafe(int a[][N],int row,int col,int num)//corrected

{

    if(rowCheck(a,row,num)==1)

    {

        if(colCheck(a,col,num)==1)

        {

            if(boxCheck(a,row-row%3,col-col%3,num)==1)

            {

              return 1; //safe

            }

        }

    }

    else

    {

        return 0;

    }


}


int unassign(int a[][N],int *row1,int *col1)//corrected

{

    for(row=0;row<N;row++)

    {

        for(col=0;col<N;col++)

        {

            if(a[row][col]==unassigned)

            {

                *row1=row;

                *col1=col;

                return 1; //unassigned

            }

        }

    }

    return 0; //all full

}


int solveSudoku(int a[][N])//corrected

{
    int row1,col1;
    

    if(unassign(a,&row1,&col1)==0)//when all full(corrected)

        return 1;//success


    for(int ar=1;ar<=N;ar++)

    {

        if(isSafe(a,row1,col1,ar)==1)//corrected

        {

                a[row1][col1]=ar;
                
                if(solveSudoku(a)==1)//corrected
                    return 1;

                
                a[row1][col1]=0;
               
        }
     
    }


    return 0;//unsuccesfull

}


int main()

{

        int a[N][N]= {{0, 0, 0, 0, 1, 0, 0, 0, 0},
                      {0, 4, 0, 2, 0, 0, 0, 9, 6},
                      {1, 0, 0, 0, 0, 0, 0, 0, 2},
                      {0, 7, 0, 5, 0, 0, 8, 2, 0},
                      {3, 0, 0, 0, 4, 0, 0, 0, 9},
                      {0, 2, 5, 0, 0, 3, 0, 6, 0},
                      {4, 0, 0, 0, 0, 9, 0, 0, 8},
                      {6, 9, 0, 0, 0, 4, 0, 7, 0},
                      {0, 0, 0, 0, 7, 0, 0, 0, 0}};

    //
    printf("THE INPUT: \n");

    output(a);

    int suc=solveSudoku(a);//corrected
   // output();
    if(suc==1)

    {
            printf("THE OUTPUT: \n");

        output(a);
}
return 0;
}//end of the main