Question

Given a linked list of integers, remove any nodes from the linked list that have values that have previously occurred in the linked list. Your function should return a reference to the head of the updated linked list. (In Python)

Answer 1

Program in Python:-

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

class LinkedList:
    # This function to initialize head
    def __init__(self):
        self.head = None

    #This function is used to insert a
    # new node at the beginning
    def insert(self, data):
        node = Node(data)
        node.next=self.head
        self.head = node

    #This function to print the LinkedList
    def printList(self):
        current  = self.head
        while current:
            print(current.data,end=" ")
            current= current.next

    #This function is used to removes duplicates
    #elements from the LinkedList
    def removeDuplicates(self):
        temp = ptr = self.head
        while temp is not None:  #Pick elements one by one
            # Compare the picked element with rest of the elements in the LinkedList
            while ptr.next is not None:
                # If duplicate element find then delete it
                if ptr.next.data == temp.data:
                    ptr.next = ptr.next.next
                else:
                    ptr = ptr.next
            temp = temp.next
            ptr = temp


l= LinkedList()
l.insert(10)
l.insert(20)
l.insert(30)
l.insert(20)
l.insert(15)
l.insert(10)
l.insert(20)
l.insert(40)
l.insert(30)


print("Elements of LinkedList before removing duplicate elements: ")
l.printList()

l.removeDuplicates()

print("\nElements of LinkedList after removing duplicate elements: ")
l.printList()

Output:-