#include<stdio.h>
int main()
{
	void function1();
	void function2();
	void function3();
	void function4();
	return 0;
	function1();
	function2();
	function3();
	function4();
}


#include <stdio.h>

int sudoku[9][9];


int in_row(int row, int num) {
    for (int i = 0; i < 9; i++) {
        if (sudoku[row][i] == num) {
            return 1;
        }
    }
    return 0;
}


int in_col(int col, int num) {
    for (int i = 0; i < 9; i++) {
        if (sudoku[i][col] == num) {
            return 1;
        }
    }
    return 0;
}


int in_box(int row, int col, int num) {
    int box_row = row / 3 * 3;
    int box_col = col / 3 * 3;
    for (int i = box_row; i < box_row + 3; i++) {
        for (int j = box_col; j < box_col + 3; j++) {
            if (sudoku[i][j] == num) {
                return 1;
            }
        }
    }
    return 0;
}


int is_valid(int row, int col, int num) {
    return !in_row(row, num) && !in_col(col, num) && !in_box(row, col, num);
}


int solve_sudoku(int row, int col) {
    if (row == 9) {
        return 1;
    }
    if (col == 9) {
        return solve_sudoku(row + 1, 0);
    }
    if (sudoku[row][col] != 0) { 
        return solve_sudoku(row, col + 1);
    }
    for (int num = 1; num <= 9; num++) { 
        if (is_valid(row, col, num)) {
            sudoku[row][col] = num;
            if (solve_sudoku(row, col + 1)) {
                return 1;
            }
            sudoku[row][col] = 0; 
        }
    }
    return 0;
}

void function4()
{
    function1();
    if (solve_sudoku(0, 0)) {
        
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                printf("%d ", sudoku[i][j]);
            }
            printf("\n");
        }
    }
    else {
        printf("No solution!\n");
    }
    return 0;
}