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

int check(int sudoku[9][9]) {
    int w[9], c[9], b[9];

    for (int i = 0; i < 9; i++) {
        for (int j = 0; j < 9; j++) {
            w[j] = 0;
            c[j] = 0;
            b[j] = 0;
        }

        for (int j = 0; j < 9; j++) {
            int k = sudoku[i][j];

            if (k == 0) continue;
            if (w[k - 1] == 1) return 0;
            w[k - 1] = 1;

            k = sudoku[j][i];

            if (k == 0) continue;
            if (c[k - 1] == 1) return 0;
            c[k - 1] = 1;

            k = sudoku[(i / 3) * 3 + j / 3][(i % 3) * 3 + j % 3];

            if (k == 0) continue;
            if (b[k - 1] == 1) return 0;
            b[k - 1] = 1;
        }
    }

    return 1;
}

int main() {
    int a[9][9] = { 0 };
    int i, j, k;

    printf("The original Sudoku matrix:\n");
    srand(time(NULL));
    printf("|-------------------|\n");

    for (i = 0; i < 9; i++) {
        for (j = 0; j < 9; j++) {
            if (j % 3 == 0) printf("|");

            if (rand() % 3 == 0) {
                do {
                    k = rand() % 9 + 1;
                } while (a[i][k - 1] != 0);

                a[i][k - 1] = k;
                printf("%d", k);
            }
            else {
                a[i][j] = 0;
                printf(".");
            }

            if (j == 8) printf("|");
            printf(" ");
        }

        if ((i + 1) % 3 == 0) printf("\n|-------------------|");
        printf("\n");
    }

    if (check(a))
        printf("True: Valid initial Sudoku matrix!\n");
    else {
        printf("False: Invalid initial Sudoku matrix!\n");
        for (i = 0; i < 9; i++) {
            for (j = i + 1; j < 9; j++) {
                for (k = i / 3 * 3; k < i / 3 * 3 + 3; k++) {
                    for (int l = i % 3 * 3; l < i % 3 * 3 + 3; l++) {
                        if ((a[i][j] != 0 && a[i][j] == a[k][l]) ||
                            (a[j][i] != 0 && a[j][i] == a[l][k])) {
                            printf("The number %d in the row %d has been used!\n", a[i][j], i + 1);
                            goto end;
                        }
                    }
                }
            }
        }
    end:;
    }

    return EXIT_SUCCESS;
}