C-Sudoku求解器-帮助理解功能

Question

I'm trying to figure out exactly what the fillSudoku function is doing in this Sudoku solver. The isAvailable checks if the number will be stopped by numbers in the same row, column, and box. The main function executes everything with checks.

Does anyone understand the functionality/process the fillSudoku function is doing?

int isAvailable(int puzzle[][9], int row, int col, int num)
{
    int rowStart = (row/3) * 3;
    int colStart = (col/3) * 3;
    int i, j;

    for(i=0; i<9; ++i)
    {
        if (puzzle[row][i] == num) return 0;
        if (puzzle[i][col] == num) return 0;
        if (puzzle[rowStart + (i%3)][colStart + (i/3)] == num) return 0;
    }
    return 1;
}

int fillSudoku(int puzzle[][9], int row, int col)
{
    int i;
    if(row<9 && col<9)
    {
        if(puzzle[row][col] != 0)
        {
            if((col+1)<9) return fillSudoku(puzzle, row, col+1);
            else if((row+1)<9) return fillSudoku(puzzle, row+1, 0);
            else return 1;
        }
        else
        {
            for(i=0; i<9; ++i)
            {
                if(isAvailable(puzzle, row, col, i+1))
                {
                    puzzle[row][col] = i+1;
                    if((col+1)<9)
                    {
                        if(fillSudoku(puzzle, row, col +1)) return 1;
                        else puzzle[row][col] = 0;
                    }
                    else if((row+1)<9)
                    {
                        if(fillSudoku(puzzle, row+1, 0)) return 1;
                        else puzzle[row][col] = 0;
                    }
                    else return 1;
                }
            }
        }
        return 0;
    }
    else return 1;
}

int main()
{
    int i, j;
    int puzzle[9][9]={{0, 0, 0, 0, 0, 0, 0, 9, 0},
                      {1, 9, 0, 4, 7, 0, 6, 0, 8},
                      {0, 5, 2, 8, 1, 9, 4, 0, 7},
                      {2, 0, 0, 0, 4, 8, 0, 0, 0},
                      {0, 0, 9, 0, 0, 0, 5, 0, 0},
                      {0, 0, 0, 7, 5, 0, 0, 0, 9},
                      {9, 0, 7, 3, 6, 4, 1, 8, 0},
                      {5, 0, 6, 0, 8, 1, 0, 7, 4},
                      {0, 8, 0, 0, 0, 0, 0, 0, 0}};

    if(fillSudoku(puzzle, 0, 0))
    {
        printf("\n+-----+-----+-----+\n");
        for(i=1; i<10; ++i)
        {
            for(j=1; j<10; ++j) printf("|%d", puzzle[i-1][j-1]);
            printf("|\n");
            if (i%3 == 0) printf("+-----+-----+-----+\n");
        }
    }
    else printf("\n\nNO SOLUTION\n\n");

    return 0;
}

Answer 1

your question:

Does anyone understand the functionality/process the fillSudoku function is doing?

the answer is Yes , most of us do understand the functionality/process.

Strongly suggest you edit your question to indicate that YOU don't understand and need some explanation.

And don't repost the same question