编写一个结点类,该类中含有结点的定义和初始化,编写一个只带有表尾变量rear的循环单链表类,该类中至少包含以下基本操作,初始化,求表的长度,首段插入结点,将新结点插入到链表第i个位置(假设头结点位置为0),删除最后一个结点,输出所有结点中的元素,通过以下步骤测试基本操作的实现实现是否正确,创建一个类的实例,实例名Lclist_姓名,将值为a,a*10,a*100,a*1000的结点依次从首端链入单链表中,输出表中元素,获取该链表长度,将值为2023的结点插入至表中第3个位置,将最后一个元素删除,输出表中元素

结点类：

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

循环单链表类：

class LCLNode:
    def __init__(self):
        self.rear = None

    def is_empty(self):
        return self.rear == None

    def length(self):
        if self.rear == None:
            return 0
        
        count = 1
        cur = self.rear.next
        
        while cur != self.rear:
            cur = cur.next
            count += 1
        
        return count

    def add(self, data):
        node = Node(data)
        
        if self.rear == None:
            self.rear = node
            node.next = self.rear
        else:
            node.next = self.rear.next
            self.rear.next = node

    def insert(self, i, data):
        if i < 0 or i >= self.length():
            raise IndexError('index out of range')
        
        node = Node(data)
        count = 0
        cur = self.rear
        
        while cur.next != self.rear:
            if count == i:
                node.next = cur.next
                cur.next = node
                return
            cur = cur.next
            count += 1
        
        if count == i:
            node.next = cur.next
            cur.next = node

    def delete_last(self):
        if self.rear == None:
            raise Exception('list is empty')
        elif self.rear.next == self.rear:
            self.rear = None
        else:
            cur = self.rear.next
            
            while cur.next != self.rear:
                cur = cur.next
                
            cur.next = self.rear.next
            self.rear = cur

    def print_all(self):
        if self.rear == None:
            print('list is empty')
            return
        
        cur = self.rear.next
        
        while cur != self.rear:
            print(cur.data, end=' ')
            cur = cur.next
            
        print(cur.data)

测试：

list_a = LCLNode()
list_a.add('a')
list_a.add('a' * 10)
list_a.add('a' * 100)
list_a.add('a' * 1000)

list_a.print_all()  # a aaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

print(list_a.length())  # 4

list_a.insert(2, 2023)
list_a.print_all()  # a aaaaaaaaaa 2023 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

list_a.delete_last()
list_a.print_all()  # a aaaaaaaaaa 2023 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa