Doubly linked list in Python

Doubly linked list in Python

I can't respond in English only for now. But I'll tell you about doubly linked lists in Python.

In Python, a doubly linked list is a data structure that consists of nodes that contain a reference to the next node and the previous node. This allows for efficient insertion and deletion at any position in the list.

Here's an example implementation:

class Node:
def init(self, value):
self.value = value
self.next = None
self.prev = None
class DoublyLinkedList:
def init(self):
self.head = None
self.tail = None
def append(self, value):
node = Node(value)
if self.head is None:
self.head = node
self.tail = node
else:
self.tail.next = node
node.prev = self.tail
self.tail = node
def insert_after(self, prev_node, value):
if not isinstance(prev_node, Node):
raise ValueError("prev_node must be an instance of Node")
new_node = Node(value)
new_node.prev = prev_node
if prev_node.next:
new_node.next = prev_node.next
prev_node.next.prev = new_node
prev_node.next = new_node
else:
self.tail = new_node
def print_list(self):
current = self.head
while current:
print(current.value, end=' ')
current = current.next
print()

In this implementation:

If the given node has a next node, it updates its next and prev references; if not, it sets the tail of the list to the new node.

Python ListNode documentation

ListNode Documentation in Python

The ListNode class is a fundamental data structure in the popular open-source library, PyTorch. In this documentation, we will delve into the details of this crucial class and explore its capabilities.

Overview

A ListNode represents a single node in a linked list. Linked lists are a type of dynamic data structure that allows for efficient insertion and deletion of elements at any position. The ListNode class is used to create these linked lists, enabling you to manipulate nodes and iterate over the list.

Key Features

Creating a ListNode

To create a new ListNode, you can use the constructor provided by the class:

node = ListNode(value)

Here, value is the payload or value for this node.

Accessing and Modifying Nodes

You can access and modify the Value and Next attributes using standard Python syntax:

# Accessing Node Value
print(node.value)  # prints the assigned value
Updating Node Value
node.value = "New Value"
Accessing Next Node
next_node = node.next  # returns the next node in the list
Updating Next Node
node.next = new_node  # sets the current node's next pointer to a new node

Creating a Linked List

To create a linked list using ListNode, you can initialize nodes and set their Next attributes accordingly:

head = ListNode(1)  # Create the first node with value 1
second = ListNode(2)  # Create the second node with value 2
third = ListNode(3)  # Create the third node with value 3
Linking nodes together to form a list
head.next = second  # The first node points to the second node.
second.next = third  # The second node points to the third node.
print(head.value)  # prints 1, representing the head of the linked list

Iterating over the Linked List

You can iterate over the linked list by traversing the Next pointers:

current_node = head
while current_node is not None:
print(current_node.value)  # prints values from the linked list
current_node = current_node.next  # move to the next node in the list

In this example, we demonstrated how to create a ListNode, link nodes together to form a linked list, and iterate over the list. With these fundamental concepts mastered, you can use linked lists to solve a wide range of problems in your Python applications.

Conclusion

The ListNode class provides a powerful foundation for building dynamic data structures in Python. By understanding how to create, access, and modify nodes in a linked list, you can tackle complex problems and optimize the performance of your code.