C打印中的数独求解器

Question

好吧所以我有一个数独求解器的所有这些代码（它没有完成，我仍然需要我找到下一个函数和合法移动函数）但我可以使用一些打印帮助。代码要求用户上传要读取的文件，然后打印出拼图。这意味着数独可以是3x3或4x4，一直到25x25。我需要帮助的是，在我的print_puzzle函数中，如何确保它以块的形式打印出来？就像它是3x3一样，这个拼图会有9个3x3盒子。希望这很有意义，反正这里是代码：

    #include <stdio.h>
    #include <stdbool.h>
    #include <string.h>
    #include <stdlib.h>
    #include <math.h>

    bool prompt_for_file (void);
    bool load_puzzle(char filename[]);
    void print_puzzle (void);
    bool solve_puzzle(void);
    bool find_next( int *row, int *col, int dir);
    bool legal_move(int num; int row; int col);

    #define MAX_SIZE 25
    #define FORWARD 1
    #define BACKWARD 0

    int puzzle[MAX_SIZE][MAX_SIZE];
    int puzzle_size;
    int block_size;


    int main(void)
    {
       if (!prompt_for_file())
       {return -1;}

       print_puzzle();

       if (solve_puzzle())
       {print_puzzle();}
       else
       {return -1;}

       return 0;
    }


    bool solve_puzzle(void)
    {
       int dir;
       int R;
       int C;
       int n;
       int previous_n;
       dir = FORWARD;
       while(find_next(&R, &C, dir))
       {
       dir= BACKWARD;
       previous_n=abs(puzzle[R][C]);
       puzzle[R][C]= 0;
       for (n=previous_n+1; n<=puzzle_size; n++)
        {
         if (legal_move(n, R, C))
         {
          puzzle[R][C] = -n;
          dir = FORWARD;
          break;
         }
        }
       }
       if (dir== FORWARD)
       {return true;}
       else
       {return false;}
    }


    void print_puzzle (void)
    {
    int r;
    int c;
    printf("\n");
    for (r=0;r<puzzle_size;r++)
       {
          for (c=0;c<puzzle_size;c++)
          {
             printf("%3d", abs(puzzle[r][c]));
    //put something in to define blocks

          }
        printf("\n");
       }
        printf("\n");
    }

    /*
    bool find_next( int *row, int *col, int dir)
    {
    *R=r;
    *C=c;

    }
    */

    bool prompt_for_file (void)
    {
        char filename[100];
       do
       {
          printf("Enter a file name (or ""quit""): ");
          scanf("%s",&filename[0]);

          if (  strcmp(filename,"quit")==0  )
          {
             filename[0]='\0';
             printf("quitting\n");
             return false;
          }

       } while( load_puzzle(filename)!=true );
       return true;
    }


    bool load_puzzle(char filename[])
    {
       int r;
       int c;
       int dummy;
       FILE *fileptr;

       // open the file but return if not successful
       fileptr = fopen(filename,"r");
       if ( fileptr==NULL)
       {
          printf("the file was not opened: %s\n", filename);
          return false;
       }
       else
       {
          printf("the file was opened: %s\n", filename);
       }

       // read the sizing info
       fscanf(fileptr,"%d",&puzzle_size);
       printf("the number of rows and cols: %d\n",puzzle_size);
       if (puzzle_size>MAX_SIZE)
       { 
        printf("puzzle is too big %d. Max size is %d\n", puzzle_size,MAX_SIZE);
        return false;
       }
               block_size=sqrt(puzzle_size);

               // read the data
               for (r=0;r<puzzle_size;r++)
               {
                  for (c=0;c<puzzle_size;c++)
                  {
                     if ( fscanf(fileptr,"%d",&puzzle[r][c])!=1 )
                     {
                        printf("insufficient number of elements\n");
                return false;
             }
          }
       }

       // check to see if all of the data was read
       // and that the end of the input file has been reached
       if (fscanf(fileptr,"%d",&dummy) ==1)
       {
           printf("WARNING: not all numbers from file were used.\n");
       }
       if (feof(fileptr))
       {
           printf("The end of the input file has been reached.\n");
       }

       fclose(fileptr);
       return true;
    }

谢谢!! :)