data structures || linked list

 from itertools import count

from logging import exception

class Node: #ele in  linked list call node,node will have data, and pointer to next

    #so create node cls with data and next

    def __init__(self,data):

        self.data=data

        self.next=None

        #start of linked list called head

class Linkedlist:

    def __init__(self):

        self.head=None

    def addinfront(self,newdata):

        # to add node in front of linked list, create new node that you wanted to add

        # point that to already existing linked list head

        #  now make new node as head of linked list

        node=Node(newdata)

        node.next=self.head

        self.head=node

      #to print the linked list, head node of linked list assign to variable

      # if variable is not none it iterate using while loop

      # prints data and next node is assign to varible

    def insertinend(self,newdata):

        # to add at end we have to check weather linked list is none or not

        #if it is none head node will be new node

        #else iterate throuth each node find next to node is none

        newnode=Node(newdata)

        if self.head is None:

            self.head=newnode

            return

        else:

            last=self.head

            while last.next:

                last=last.next

            last.next=newnode

    def insertlist(self,newlist):

        #self.head=None

        for date in newlist:

            self.insertinend(date)

    def length(self):

        count=0

        temp=self.head

        while temp:

            count+=1

            temp=temp.next

        return count

    def remove_ele_index(self,index):

        if index<0 or index>=self.length():

            raise exception("Invalid index")

        if index==0:

            self.head=self.head.next

       

        count=0

        temp=self.head

        while temp:

            if count==index-1:

                temp.next=temp.next.next

                break

            count+=1

            temp=temp.next    

       

    def Afterpreviousnode(self,previousnode,newdata):

        if previousnode is None:

            print("Enter the valid Node")

        else:

            newnode=Node(newdata)

            newnode.next=previousnode.next

            previousnode.next=newnode

    def insert_at(self,index,newdata):

        if index<0 or index>=self.length():

            raise exception("Invalid index")

        if index==0:

            self.addinfront(newdata)

            return

        count=0

        temp=self.head

        while temp:

            if count==index-1:

                newnode=Node(newdata)

                newnode.next=temp.next.next

                temp.next=newnode

                break

            count+=1

            temp=temp.next

    def print(self):

        temp=self.head

        while temp:

            print(temp.data,end=" ")

            temp=temp.next

if __name__=="__main__":

    llist=Linkedlist()

    llist.head=Node(4)

    second=Node(19)

    Third=Node(8)

 

    llist.head.next=second

    second.next=Third

    llist.addinfront(1)

    llist.addinfront(55)

    llist.addinfront(5)

    llist.insertinend(99)

    llist.insertlist(["apple","banana","mango"])

    llist.Afterpreviousnode(Third,0)

    llist.remove_ele_index(3)

    llist.insert_at(3,33)

    llist.insert_at(0,1000)

   

    llist.print()

    print("lenth is:",llist.length())