main

def print_board(board):
    for i in range(len(board)):
        if i % 3 == 0 and i != 0:
            print("- - - - - - - - - - -")
        
        for j in range(len(board[i])):
            if j % 3 == 0 and j != 0:
                print(" | ", end="")
            
            if j == 8:
                print(board[i][j])
            else:
                print(str(board[i][j]) + " ", end="")

def find_empty(board):
    for i in range(len(board)):
        for j in range(len(board[i])):
            if board[i][j] == 0:
                return (i, j)
    return None

def is_valid(board, num, position):
    # Check row
    for i in range(len(board[0])):
        if board[position[0]][i] == num and position[1] != i:
            return False
    
    # Check column
    for i in range(len(board)):
        if board[i][position[1]] == num and position[0] != i:
            return False
    
    # Check 3x3 box
    box_row = position[0] // 3
    box_col = position[1] // 3
    
    for i in range(box_row * 3, box_row * 3 + 3):
        for j in range(box_col * 3, box_col * 3 + 3):
            if board[i][j] == num and (i, j) != position:
                return False
    
    return True

def solve_sudoku(board):
    find = find_empty(board)
    if not find:
        return True
    else:
        row, col = find
    
    for num in range(1, 10):
        if is_valid(board, num, (row, col)):
            board[row][col] = num
            
            if solve_sudoku(board):
                return True
            
            board[row][col] = 0
    
    return False

# Example Sudoku board (0 represents empty cells)
board = [
    [5, 3, 0, 0, 7, 0, 0, 0, 0],
    [6, 0, 0, 1, 9, 5, 0, 0, 0],
    [0, 9, 8, 0, 0, 0, 0, 6, 0],
    [8, 0, 0, 0, 6, 0, 0, 0, 3],
    [4, 0, 0, 8, 0, 3, 0, 0, 1],
    [7, 0, 0, 0, 2, 0, 0, 0, 6],
    [0, 6, 0, 0, 0, 0, 2, 8, 0],
    [0, 0, 0, 4, 1, 9, 0, 0, 5],
    [0, 0, 0, 0, 8, 0, 0, 7, 9]
]

print("Sudoku Board:")
print_board(board)
solve_sudoku(board)
print("\nSolution:")
print_board(board)