def possible(sudoku, x, y, n):
    """验证值的可能性"""
    for i in range(9):
        if sudoku[i][y] == n:
            return False

    for j in range(9):
        if sudoku[x][j] == n:
            return False

    # 所在小九宫格第一个元素的坐标
    grid_x = x // 3 * 3
    grid_y = y // 3 * 3
    for i in range(3):
        for j in range(3):
            xx = grid_x + j
            yy = grid_y + i
            if sudoku[xx][yy] == n:
                return False
    return True


def solve(sudoku):
    """数独求解
    深度优先穷举法
    """
    for x in range(9):
        for y in range(9):
            if sudoku[x][y] == 0:
                for n in range(1, 10):
                    if possible(sudoku, x, y, n):
                        sudoku[x][y] = n
                        solve(sudoku)
                        sudoku[x][y] = 0
                return
    for row in sudoku:
        print(row)


if __name__ == '__main__':
    sudoku = [
        [0, 9, 0, 1, 0, 0, 3, 7, 8],
        [0, 0, 0, 7, 0, 9, 0, 0, 0],
        [0, 1, 0, 4, 0, 8, 0, 0, 6],
        [0, 0, 0, 2, 0, 0, 6, 5, 9],
        [0, 0, 0, 0, 4, 3, 0, 0, 0],
        [0, 5, 1, 0, 0, 0, 0, 0, 0],
        [0, 0, 2, 3, 5, 1, 7, 0, 0],
        [0, 6, 0, 8, 9, 0, 5, 0, 2],
        [0, 0, 0, 0, 0, 2, 8, 0, 0]
    ]
    solve(sudoku)