#include <stdio.h>
#include <stdlib.h>
#include <time.h>


void generate_sudoku(int board[9][9]) {
    srand(time(NULL));
    int i,j;
    for (i = 0; i < 9; i++) {
        for ( j = 0; j < 9; j++) {
            board[i][j] =rand()%10;
            
        }
    }
}

void print_sudoku(int board[9][9]) {
	int i,j;
    for ( i = 0; i < 9; i++) {
        for (j = 0; j < 9; j++) {
            printf("%d ", board[i][j]);
        }
        printf("\n");
    }
}


int test(int board[9][9]) {
	int i,j,k,p,q;
    for (i = 0; i < 9; i++) {
        for (j = 0; j < 9; j++) {
            if (board[i][j] != 0) {
                for (k = 0; k < 9; k++) {
                    if (k != j && board[i][j] == board[i][k]) {
                        printf("False:Invalid initial Sudoku matrix!\n");
                        printf("The number %d in the col %d has been used!\n", board[i][j], j + 1);
                        return 0;
                        break;
                    }
                    if (k != i && board[i][j] == board[k][j]) {
                        printf("False:Invalid initial Sudoku matrix!\n");
                        printf("The number %d in the row %d has been used!\n", board[i][j], i + 1);
                        return 0;      
						break;          
                    }
                }
                for (p = i / 3 * 3; p < i / 3 * 3 + 3; p++) {
                    for (q = j / 3 * 3; q < j / 3 * 3 + 3; q++) {
                        if ((p != i || q != j) && board[i][j] == board[p][q]) {
                            printf("False:Invalid initial Sudoku matrix!\n");
                            printf("The number %d in the block %d has been used!\n", board[i][j], (p / 3) * 3 + q / 3 + 1);
                            return 0;
                            break;
                        }
                    }
                }
            }
        }
    }
    printf("True:Valid initial Sudoku matrix!\n");
    return 1;
}


int add(int board[9][9]) {
	int row,col,num;
    for (row = 0; row < 9; row++) {
        for (col = 0; col < 9; col++) {
            if (board[row][col] == 0) {
                for (num = 1; num <= 9; num++) {
                    if (test(board)) {
                        board[row][col] = num;
                        if (add(board)) {
                            return 1;
                        } 
					else {
                        board[row][col] = 0;
                        }
                    }
                }
                return 0;          
            }
        }
    }
    return 1;
}


int main() {
    int board[9][9];
    generate_sudoku(board);
    printf("The original Sudoku matrix:\n");
    print_sudoku(board);
    test(board);
    if (add(board)) {
    	printf("The solution of Sudoku matrix:\n");
        print_sudoku(board);
    } else {
        printf("No solution\n");
    }
    return 0;
}