Python的单循环链表

单循环链表是一种特殊的链表，它的最后一个节点的 next 指针指向头节点，形成一个环。

以下是 Python 实现单循环链表的代码：

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

class CircularLinkedList:
    def __init__(self):
        self.head = None

    def add_node(self, data):
        new_node = Node(data)
        if self.head is None:
            self.head = new_node
            new_node.next = self.head
        else:
            current = self.head
            while current.next != self.head:
                current = current.next
            current.next = new_node
            new_node.next = self.head

    def display(self):
        if self.head is None:
            print("List is empty")
        else:
            current = self.head
            while current.next != self.head:
                print(current.data, end=" ")
                current = current.next
            print(current.data, end=" ")

    def remove_node(self, key):
        if self.head is None:
            print("List is empty")
            return

        if self.head.data == key:
            current = self.head
            while current.next != self.head:
                current = current.next
            current.next = self.head.next
            self.head = self.head.next
        else:
            current = self.head
            prev = None
            while current.next != self.head:
                prev = current
                current = current.next
                if current.data == key:
                    prev.next = current.next
                    current = current.next

    def search_node(self, key):
        if self.head is None:
            print("List is empty")
            return
        current = self.head
        while current.next != self.head:
            if current.data == key:
                print("Node found")
                return
            current = current.next
        if current.data == key:
            print("Node found")
            return
        print("Node not found")


# Test the CircularLinkedList class
clist = CircularLinkedList()

clist.add_node(1)
clist.add_node(2)
clist.add_node(3)
clist.add_node(4)

print("Original List")
clist.display()

clist.remove_node(4)
print("\nList after removing node with data=4")
clist.display()

clist.search_node(2)
clist.search_node(5)

输出结果：

Original List
1 2 3 4 
List after removing node with data=4
1 2 3 
Node found
Node not found

上面的代码实现了单循环链表的基本操作，包括添加节点、删除节点、查找节点和显示链表。