Python Program For Removing Duplicates From A Sorted Linked List

# Python3 program to remove duplicate
# nodes from a sorted linked list 

# Node class 
class Node: 

    # Constructor to initialize 
    # the node object 
    def __init__(self, data): 
        self.data = data 
        self.next = None

class LinkedList: 

    # Function to initialize head 
    def __init__(self): 
        self.head = None

    # Function to insert a new node 
    # at the beginning 
    def push(self, new_data): 
        new_node = Node(new_data) 
        new_node.next = self.head 
        self.head = new_node 

    # Given a reference to the head of a 
    # list and a key, delete the first 
    # occurrence of key in linked list 
    def deleteNode(self, key): 
        
        # Store head node 
        temp = self.head 

        # If head node itself holds the 
        # key to be deleted 
        if (temp is not None): 
            if (temp.data == key): 
                self.head = temp.next
                temp = None
                return

        # Search for the key to be deleted, 
        # keep track of the previous node as
        # we need to change 'prev.next' 
        while(temp is not None): 
            if temp.data == key: 
                break
            prev = temp 
            temp = temp.next

        # If key was not present in 
        # linked list 
        if(temp == None): 
            return

        # Unlink the node from linked list 
        prev.next = temp.next

        temp = None

    # Utility function to print the 
    # linked LinkedList 
    def printList(self): 
        temp = self.head 
        while(temp): 
            print(temp.data , end = ' ')
            temp = temp.next
    
    # This function removes duplicates 
    # from a sorted list         
    def removeDuplicates(self):
        temp = self.head
        if temp is None:
            return
        while temp.next is not None:
            if temp.data == temp.next.data:
                new = temp.next.next
                temp.next = None
                temp.next = new
            else:
                temp = temp.next
        return self.head

# Driver Code 
llist = LinkedList() 

llist.push(20) 
llist.push(13) 
llist.push(13)
llist.push(11)
llist.push(11)
llist.push(11)
print ("Created Linked List: ")
llist.printList() 
print()
print("Linked List after removing", 
      "duplicate elements:")
llist.removeDuplicates()
llist.printList() 
# This code is contributed by Dushyant Pathak.

# Python3 Program to remove duplicates
# from a sorted linked list 
import math

# Link list node 
class Node: 
    def __init__(self, data): 
        self.data = data 
        self.next = None

# The function removes duplicates 
# from a sorted list 
def removeDuplicates(head): 
    
    # Pointer to store the pointer 
    # of a node to be deleted to_free 
    
    # Do nothing if the list is empty 
    if (head == None): 
        return

    # Traverse the list till last node 
    if (head.next != None): 
        
        # Compare head node with next node 
        if (head.data == head.next.data): 
            
            # The sequence of steps is important. 
            # to_free pointer stores the next of head 
            # pointer which is to be deleted. 
            to_free = head.next
            head.next = head.next.next
            
            # free(to_free) 
            removeDuplicates(head) 
        
        # This is tricky: only advance if no deletion
        else: 
            removeDuplicates(head.next) 
        
    return head

# UTILITY FUNCTIONS 
# Function to insert a node at the 
# beginning of the linked list 
def push(head_ref, new_data): 
    
    # Allocate node 
    new_node = Node(new_data) 
            
    # Put in the data 
    new_node.data = new_data 
                
    # Link the old list off the 
    # new node 
    new_node.next = head_ref     
        
    # Move the head to point to the 
    # new node 
    head_ref = new_node
    return head_ref

# Function to print nodes in a given 
# linked list 
def printList(node): 
    while (node != None): 
        print(node.data, end = " ") 
        node = node.next
    
# Driver code
if __name__=='__main__': 

    # Start with the empty list 
    head = None
    
    # Let us create a sorted linked list
    # to test the functions 
    # Created linked list will be 
    # 11.11.11.13.13.20 
    head = push(head, 20) 
    head = push(head, 13) 
    head = push(head, 13) 
    head = push(head, 11) 
    head = push(head, 11) 
    head = push(head, 11)                                 

    print("Linked list before duplicate removal ",
           end = "") 
    printList(head) 

    # Remove duplicates from linked list 
    removeDuplicates(head) 

    print("Linked list after duplicate removal ",
           end = "") 
    printList(head)         
    
# This code is contributed by Srathore

# Python3 program to remove duplicates 
# from a sorted linked list  
import math 
  
# Link list node  
class Node:  
    
    def __init__(self, data):        
        self.data = data  
        self.next = None
  
# The function removes duplicates  
# from the given linked list 
def removeDuplicates(head):  
    
    # Do nothing if the list consist of 
    # only one element or empty  
    if (head == None and 
        head.next == None):
        return
    
    # Construct a pointer 
    # pointing towards head
    current = head
    
    # Initialise a while loop till the 
    # second last node of the linkedlist 
    while (current.next):
        
        # If the data of current and next
        # node is equal we will skip the
        # node between them
        if current.data == current.next.data:
            current.next = current.next.next
            
        # If the data of current and 
        # next node is different move
        # the pointer to the next node
        else:
            current = current.next
    
    return
  
# UTILITY FUNCTIONS  
# Function to insert a node at the  
# beginning of the linked list  
def push(head_ref, new_data):  
    
    # Allocate node  
    new_node = Node(new_data)  
              
    # Put in the data  
    new_node.data = new_data  
                  
    # Link the old list off 
    # the new node  
    new_node.next = head_ref      
          
    # Move the head to point
    # to the new node  
    head_ref = new_node 
    
    return head_ref 
  
# Function to print nodes 
# in a given linked list  
def printList(node):  
    
    while (node != None):  
        print(node.data, end = " ")  
        node = node.next
      
# Driver code 
if __name__=='__main__':  
  
    head = None    
    head = push(head, 20)  
    head = push(head, 13)  
    head = push(head, 13)  
    head = push(head, 11)  
    head = push(head, 11)  
    head = push(head, 11)                                  
  
    print("List before removal of "  
          "duplicates ", end = "")  
    printList(head)  
  
    removeDuplicates(head)  
  
    print("List after removal of "  
          "elements ", end = "")            
    printList(head)          
# This code is contributed by MukulTomar