Python单链表实现、带尾结点的单链表实现

# LList.py

class LNode:
    def __init__(self, elem, next_=None):
        self.elem = elem
        self.next = next_

class linkedListUnderUnderflow(ValueError):
    pass

class LList:
    def __init__(self) -> None:
        self.head = None

    # 判空
    def is_empty(self):
        return self.head is None
    
    # 表首插入
    def prepend(self, elem):
        self.head = LNode(elem, self.head)

    # 表首删除
    def pop(self):
        if self.head is None:
            raise linkedListUnderUnderflow("in pop")
        e = self.head.elem
        self.head = self.head.next

    # 遍历
    def for_each(self):
        temp_list = []
        p = self.head
        while p:
            temp_list.append(p.elem)
            p = p.next
        return temp_list
    
    # 后端操作
    def append(self, elem_):
        if self.head is None:
            self.head = LNode(elem_)
            return
        p = self.head
        while p.next:
            p = p.next
        p.next = LNode(elem_)
    
    # 删除最后一个元素
    def pop_last(self):
        if self.head is None:
            raise linkedListUnderUnderflow("in pop_last")
        if self.head.next is None:
            e = self.head.elem
            self.head = None
            return e
        p = self.head
        while p.next.next:
            p = p.next
        e = p.next.elem
        p.next = None
        return e

    # 逆转链表
    def reverse(self):
        new_queen = None
        while self.head:
            pointer = self.head
            self.head = pointer.next
            pointer.next = new_queen
            new_queen = pointer
        self.head = new_queen

if __name__ == '__main__':
    llist = LList()
    for value in range(10):
        llist.append(value)
    llist.pop_last()
    ret = llist.for_each()
    print(ret)
    llist.reverse()
    ret = llist.for_each()
    print(ret)

# LList1.py

from LList import *

class LList1(LList):
    def __init__(self) -> None:
        LList.__init__()
        self.rear = None
    
    # 前端插入
    def prepend(self, elem):
        if self.head:
            self.head = LNode(elem, self.head) 
        else:
            self.head = LNode(elem)
            self.rear = self.head
    
    # 后端插入
    def append(self, elem):
        if self.head is None:
            self.head = LNode(elem, self.head)
            self.rear = self.head
        else:
            self.rear.next = LNode(elem)
            self.rear = self.rear.next
    
    # 后端删除
    def pop_last(self):
        if self.head is None:
            raise linkedListUnderUnderflow("pop_last")
        p = self.head
        if p.next is None:
            e = self.head.elem
            self.head = None
            return e
        while p.next.next:
            p = p.next
        e = p.next.elem
        p.next = None
        self.rear = p
        return e


if __name__ == '__main__':
    llist = LList()
    for i in range(1, 11):
        llist.append(i)
    print(llist.for_each())
    print(llist.pop_last())
    print(llist.for_each())