#include <stdio.h>
int sudoku[9][9];
void print_sudoku(int sudoku[9][9]) {
    for (int i = 0; i < 9; i++) {
        if (i % 3 == 0 && i != 0) {
            printf("-------------------------\n");
        }
        for (int j = 0; j < 9; j++) {
            if (j % 3 == 0 && j != 0) {
                printf("| ");
            }
            printf("%d ", sudoku[i][j]);
        }
        printf("\n");
    }
}
int is_sudoku(int sudoku[9][9]) {
    for (int i = 1; i <= 3; i++)
    {
        int num[10] = { 0 };
        for (int j = 1; j <= 3; j++)
        {
            for (int k = 0; k < 9; k++)
            {
                num[(sudoku[i * j - 1][k])]++;
                if (num[(sudoku[i * j - 1][k])] >1 && sudoku[i * j - 1][k] != 0)
                {
                    printf("False:Invalid initial Sudoku matrix!\n");
                    for (int a = (i - 1) * 3; a <= i * j - 1; a++)
                    {
                        for (int c = 0; c < 9; c++)
                        {
                            if (sudoku[a][c] == sudoku[i * j - 1][k])
                            {
                                printf("The number %d in the col %d has been used!\n", sudoku[i * j - 1][k], a + 1);
                                return 0;
                            }
                        }
                    }
                }
            }

        }
        for (int l = 1; l < 10; l++)
        {
            if (num[l] < 1)
            {
                printf("False:Invalid initial Sudoku matrix!\n");
                printf("The number %d has not been used\n", l);
                return 0;
            }
        }
    }
    printf("True:Valid initial Sudoku matrix!\n");
    return 1;
}
int findvalue(int sudoku[9][9], int i, int j)
{
    int m, n, k;
    int temp[10] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
    for (k = 1; k < 10; k++)
    {
        if (temp[sudoku[i][k - 1]] == 0)
            temp[sudoku[i][k - 1]] = sudoku[i][k - 1];
        if (temp[sudoku[k - 1][j]] == 0)
            temp[sudoku[k - 1][j]] = sudoku[k - 1][j];
    }
    for (m = 0; m < 3; m++)
        for (n = 0; n < 3; n++)
            if (temp[sudoku[i / 3 * 3 + m][j / 3 * 3 + n]] == 0)
                temp[sudoku[i / 3 * 3 + m][j / 3 * 3 + n]] = sudoku[i / 3 * 3 + m][j / 3 * 3 + n];
    for (k = 1; k < 10; k++)
        if (temp[k] == 0)
        {
            temp[0]++;
            m = k;
        }
    if (temp[0] == 0)
        return -1;
    else if (temp[0] == 1)
        return m;
    else
        return 0;
}
int main() {
    int flag;
    int sudoku[9][9] = { {0, 3, 0, 0, 0, 7, 0, 0, 0},

  {1, 2, 5, 0, 0, 9, 4, 0, 0},

  {0, 7, 9, 1, 0, 0, 0, 3, 0},

  {0, 0, 6, 0, 8, 0, 0, 9, 1},

  {0, 0, 0, 9, 5, 1, 0, 0, 0},

  {9, 1, 0, 0, 7, 0, 5, 0, 0},

  {0, 9, 0, 0, 0, 5, 7, 4, 0},

  {0, 0, 8, 7, 0, 0, 2, 6, 9},

  {0, 0, 0, 4, 0, 0, 0, 5, 0} };
    printf("The original Sudoku matrix:\n");  
    print_sudoku(sudoku);
    if (!is_sudoku(sudoku))
    {
        printf("No solution!");
        return 0;
    }
    if (is_sudoku(sudoku))
    {
        int i, j, temp, empty = 0;
        for (i = 0; i < 9; i++)
        {
            for (j = 0; j < 9; j++)
                if (sudoku[i][j] == 0)
                    empty++;
        }
        while (empty)

        {
            for (i = 0; i < 9; i++)

            {
                for (j = 0; j < 9; j++)

                {
                    if (sudoku[i][j] == 0)

                    {
                        temp = findvalue(sudoku, i, j);

                        if (temp == -1)

                        {
                            printf("No solution！\n");
                            return 1;

                        }

                        sudoku[i][j] = temp;

                        if (temp != 0)empty--;

                    }

                }

            }

        }
        for (i = 0; i < 9; i++)

        {
            for (j = 0; j < 9; j++)

                printf("%d ", sudoku[i][j]);

            printf("\n");

        }
    }
        return 0;
}