在双向链表的开头插入新节点的Python程序

当需要在双向链表的开头插入新节点时，需要创建一个“Node”类。在此类中，有三个属性，即节点中存在的数据、访问链接列表的下一个节点和访问链接列表的上一个节点。

以下是相同的演示 –

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示例

class Node:
    def __init__(self, my_data):
        self.prev = None
        self.data = my_data
        self.next = None
class double_list:
    def __init__(self):
        self.head = None
        self.tail = None
    def add_data_at_start(self, my_data):
        new_node = Node(my_data)
        if(self.head == None):
            self.head = self.tail = new_node
            self.head.previous = None
            self.tail.next = None
        else:
            self.tail.previous = new_node
            new_node.next = self.head
            new_node.previous = None
            self.head = new_node
    def print_it(self):
        curr = self.head
        if (self.head == None):
            print("The list is empty")
            return
        print("The nodes in the doubly linked list are :")
        while curr != None:
            print(curr.data)
            curr = curr.next
my_instance = double_list()
print("Elements are being added to the beginning of doubly linked list")
my_instance.add_data_at_start(10)
my_instance.print_it()
my_instance.add_data_at_start(24)
my_instance.print_it()
my_instance.add_data_at_start(54)
my_instance.print_it()
my_instance.add_data_at_start(77)
my_instance.print_it()
my_instance.add_data_at_start(92)
my_instance.print_it()

输出

Elements are being added to the beginning of doubly linked list
The nodes in the doubly linked list are :
10
The nodes in the doubly linked list are :
24
10
The nodes in the doubly linked list are :
54
24
10
The nodes in the doubly linked list are :
77
54
24
10
The nodes in the doubly linked list are :
92
77
54
24
10