Linked list.py

# Create a Node class to create a node
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
 
# Create a LinkedList class
 
 
class LinkedList:
    def __init__(self):
        self.head = None
 
    # Method to add a node at begin of LL
    def insertAtBegin(self, data):
        new_node = Node(data)
        if self.head is None:
            self.head = new_node
            return
        else:
            new_node.next = self.head
            self.head = new_node
 
    # Method to add a node at any index
    # Indexing starts from 0.
    def insertAtIndex(self, data, index):
        new_node = Node(data)
        current_node = self.head
        position = 0
        if position == index:
            self.insertAtBegin(data)
        else:
            while(current_node != None and position+1 != index):
                position = position+1
                current_node = current_node.next
 
            if current_node != None:
                new_node.next = current_node.next
                current_node.next = new_node
            else:
                print("Index not present")
 
    # Method to add a node at the end of LL
 
    def insertAtEnd(self, data):
        new_node = Node(data)
        if self.head is None:
            self.head = new_node
            return
 
        current_node = self.head
        while(current_node.next):
            current_node = current_node.next
 
        current_node.next = new_node
 
    # Update node of a linked list
        # at given position
    def updateNode(self, val, index):
        current_node = self.head
        position = 0
        if position == index:
            current_node.data = val
        else:
            while(current_node != None and position != index):
                position = position+1
                current_node = current_node.next
 
            if current_node != None:
                current_node.data = val
            else:
                print("Index not present")
 
    # Method to remove first node of linked list
 
    def remove_first_node(self):
        if(self.head == None):
            return
 
        self.head = self.head.next
 
    # Method to remove last node of linked list
    def remove_last_node(self):
 
        if self.head is None:
            return
 
        current_node = self.head
        while(current_node.next.next):
            current_node = current_node.next
 
        current_node.next = None
 
    # Method to remove at given index
    def remove_at_index(self, index):
        if self.head == None:
            return
 
        current_node = self.head
        position = 0
        if position == index:
            self.remove_first_node()
        else:
            while(current_node != None and position+1 != index):
                position = position+1
                current_node = current_node.next
 
            if current_node != None:
                current_node.next = current_node.next.next
            else:
                print("Index not present")
 
    # Method to remove a node from linked list
    def remove_node(self, data):
        current_node = self.head
 
        while(current_node != None and current_node.next.data != data):
            current_node = current_node.next
 
        if current_node == None:
            return
        else:
            current_node.next = current_node.next.next
 
    # Print the size of linked list
    def sizeOfLL(self):
        size = 0
        if(self.head):
            current_node = self.head
            while(current_node):
                size = size+1
                current_node = current_node.next
            return size
        else:
            return 0
 
    # print method for the linked list
    def printLL(self):
        current_node = self.head
        while(current_node):
            print(current_node.data)
            current_node = current_node.next
 
 
# create a new linked list
llist = LinkedList()
 
# add nodes to the linked list
llist.insertAtEnd('a')
llist.insertAtEnd('b')
llist.insertAtBegin('c')
llist.insertAtEnd('d')
llist.insertAtIndex('g', 2)
 
# print the linked list
print("Node Data")
llist.printLL()
 
# remove a nodes from the linked list
print("\nRemove First Node")
llist.remove_first_node()
print("Remove Last Node")
llist.remove_last_node()
print("Remove Node at Index 1")
llist.remove_at_index(1)
 
 
# print the linked list again
print("\nLinked list after removing a node:")
llist.printLL()
 
print("\nUpdate node Value")
llist.updateNode('z', 0)
llist.printLL()
 
print("\nSize of linked list :", end=" ")
print(llist.sizeOfLL())