TypeError: unsupported operand type(s) for //: 'NoneType' and 'int'

Question

我在用python写一个解数独问题的程序，在迭代的过程中第二步总是会出现这样一个错误，改了很多次都绕不开这一条。

初学者，拜托了。。

代码如下：

def row(i, sudoku):
    # 返回一行
    row_list = []
    for q in range((i-1)*9, (i-1)*9+9):
        row_list.append(sudoku[q])

    return row_list


def col(j, sudoku):
    # 返回一列
    col_list = []
    for w in range((j-1) % 9, 80, 9):
        col_list.append(sudoku[w])

    return col_list


def sub(i, j, sudoku):
    # 返回一宫
    sub_list = []
    """多个条件得到宫数，待优化"""
    if i <= 3:
        if j <= 3:
            e = 1
            r = 1
        elif j <= 6:
            e = 2
            r = 4
        else:
            e = 3
            r = 7
    elif i <= 6:
        if j <= 3:
            e = 4
            r = 28
        elif j <= 6:
            e = 5
            r = 31
        else:
            e = 6
            r = 34
    else:
        if j <= 3:
            e = 7
            r = 55
        elif j <= 6:
            e = 8
            r = 58
        else:
            e = 9
            r = 61

    """e为宫数，r为该宫的第一个数字，手动计算得到的"""

    for t in range(r - 1, r + 2):
        sub_list.append(sudoku[t])
    for t in range(r + 8, r + 11):
        sub_list.append(sudoku[t])
    for t in range(r + 17, r + 20):
        sub_list.append(sudoku[t])

    return sub_list


def problem(sudoku):
    # 找到空点
    problem_list = []
    for z in range(0, 80):
        if sudoku[z] == 0:
            problem_list.append(z)

    return problem_list


def start_problem(sudoku):
    """第一个空点"""
    problem_list = problem(sudoku)
    x = problem_list[0]
    return x


def next_problem(i, j, sudoku):
    # 下一个空格
    x = turn(i, j)
    if sudoku[x] == 0:
        for y in range(x, 80):
            if sudoku[y] == 0:
                return y + 1


def turn(i, j):
    """行列位置转列表位置"""
    z = (i - 1) * 9 + j - 1
    return z


def get_i(x):
    """列表位置得行数"""
    i = 0
    i = x // 9 + 1
    return i


def get_j(x):
    """列表位置得列数"""
    j = 0
    j = x % 9 + 1
    return j


def check(number, x, sudoku):
    """数独规则"""
    i = get_i(x)
    j = get_j(x)
    row_list = row(i, sudoku)
    col_list = col(j, sudoku)
    sub_list = sub(i, j, sudoku)
    if number not in row_list and number not in col_list and number not in sub_list:
        return True
    else:
        return False


def available(i, j, sudoku):
    """一个位置的备选数字"""
    available_list = []
    row_list = row(i, sudoku)
    col_list = col(j, sudoku)
    sub_list = sub(i, j, sudoku)
    for number in range(1, 10):
        if number not in row_list and number not in col_list and number not in sub_list:
            available_list.append(number)

    return available_list


def try_fill(i, j, sudoku):
    """一格尝试"""
    a = turn(i, j)

    for value in available(i, j, sudoku):
        if sudoku[a] == 0:
            sudoku[a] = value
            b = 0
            b = next_problem(i, j, sudoku)
            w = get_i(b)
            e = get_j(b)
            try_fill(w, e, sudoku)



def fill(sudoku):
    """填空"""
    x = start_problem(sudoku)
    i = get_i(x)
    j = get_j(x)
    try_fill(i, j, sudoku)

    return sudoku


def answer(sudoku):
    """最终答案"""
    fill(sudoku)
    print(sudoku)

错误如下：

Traceback (most recent call last):
File "C:/Users/yl/PycharmProjects/shudu/sudo.py", line 215, in
fill(sudoku2)
File "C:/Users/yl/PycharmProjects/shudu/sudo.py", line 171, in fill
try_fill(i, j, sudoku)
File "C:/Users/yl/PycharmProjects/shudu/sudo.py", line 160, in try_fill
w = get_i(b)
File "C:/Users/yl/PycharmProjects/shudu/sudo.py", line 114, in get_i
i = x // 9 + 1
TypeError: unsupported operand type(s) for //: 'NoneType' and 'int'