数据结构双向链表的创建代码

双向链表是一种特殊的数据结构，每个节点包含两个指针，一个指向前一个节点，另一个指向后一个节点。这里是一个简单的Python实现双向链表节点和链表的示例：

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

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

    # 插入节点到链表头部
    def insert_at_beginning(self, data):
        new_node = Node(data)
        if self.head is not None:
            new_node.next = self.head
        self.head.prev = new_node
        self.head = new_node

    # 插入节点到链表尾部
    def insert_at_end(self, data):
        new_node = Node(data)
        if self.head is not None:
            current = self.head
            while current.next:
                current = current.next
            current.next = new_node
            new_node.prev = current

    # 删除指定节点
    def delete_node(self, key):
        current = self.head
        if current and current.data == key:
            self.head = current.next
            if self.head:
                self.head.prev = None
            return

        prev = None
        while current and current.data != key:
            prev = current
            current = current.next

        if current is None:
            return

        prev.next = current.next
        if current.next:
            current.next.prev = prev

# 示例使用
dll = DoublyLinkedList()
dll.insert_at_beginning(1)
dll.insert_at_end(3)