Deletion in Linked List in DSA Python

Program 1

# Impelmentation of Single Linked List

# class for size of Node
class Node:
    def __init__(self):
        self.data=None
        self.add=None


class LinkedList:
    def __init__(self):
          self.start=None
          self.count=0

 #method for create list
    def createList(self):
       n=int(input("Enter an element"))
       self.start=Node()
       self.start.data=n
       self.start.add=None
       temp=self.start
       self.count=self.count+1
       ch=input("Want to continue(Y/N)")
       while(ch=="Y"):
           n=int(input("Enter an element"))
           newnode=Node()
           newnode.data=n
           newnode.add=None
           temp.add=newnode
           temp=newnode
           self.count=self.count+1
           ch=input("Want to continue(Y/N)")

#method for display list
    def displayList(self):
           if(self.start==None):
                print("List is empty")
           else:
                print("Elements of List: ")    
                temp=self.start
                while(temp!=None):
                     print(temp.data,end=" ")
                     temp=temp.add
                print("\nTotal Node is: ",self.count)

#method for insert node at first position
    def insertFirst(self):
        if(self.start==None):
              print("List is empty")
        else:
             n=int(input("Enter an element for insert"))
             newnode=Node()
             newnode.data=n
             newnode.add=None
             newnode.add=self.start
             self.start=newnode
             self.count=self.count+1
#method for insert node at last position
    def insertLast(self):
        if(self.start==None):
              print("List is empty")
        else:
            n=int(input("Enter an element for insert"))
            newnode=Node()
            newnode.data=n
            newnode.add=None
            temp=self.start
            while(temp.add!=None):
                       temp=temp.add
            temp.add=newnode
            self.count=self.count+1
            
#method for insert node at middle position
    def insertMiddle(self):
        if(self.start==None):
              print("List is empty")
        else:
            n=int(input("Enter an element for insert"))
            newnode=Node()
            newnode.data=n
            newnode.add=None
            pos=int(input("Enter the position"))
            if(pos>self.count):
                 print("Invalid position")
            else:     
                i=1
                next=self.start
                while(i<pos):
                     prev=next
                     next=next.add
                     i=i+1
                prev.add=newnode
                newnode.add=next                 
                self.count=self.count+1
                       

    # Delete node from First                    
    def deleteFirst(self):
        if(self.start==None):
              print("List is empty")
        else:
             print("Deleted node is : ",self.start.data)
             self.start=self.start.add
             self.count=self.count-1
    
    # Delete node from Middle  
    def deleteMiddle(self): 
        if(self.start==None):
              print("List is empty")
        else:
          pos=int(input("Enter the position for delete"))   
          if(pos>self.count):
               print("Invalid position")
          else:
               i=1
               next=self.start
               while(i<pos):
                    prev=next
                    next=next.add
                    i=i+1

               temp=next  
               next=next.add                   
               prev.add=next
               print("Deleted node is: ",temp.data)
               temp=None
               self.count=self.count-1



    # Delete node from Last
    def deleteLast(self):
        if(self.start==None):
              print("List is empty")
        else:
            last=self.start
            while(last.add!=None):
                  prev=last
                  last=last.add
            print("Deleted node is :",last.data)                  
            prev.add=None
            last=None
        self.count=self.count-1


# Main Menu

mylist=LinkedList()
while(1):
    print("\n--------------------------Linked List Menu-------------------------\n")
    print("1.Create")
    print("2.Display")
    print("3.Insert First")
    print("4.Insert Middle")
    print("5.Insert Last")
    print("6.Delete First")
    print("7.Delete Middle")
    print("8.Delete Last")
    print("9.Exit")
    print("\n---------------------------------------------------------------------\n")
    choice=int(input("Enter your choice"))
    if(choice==1):
          mylist.createList()
    elif(choice==2):
          mylist.displayList()
    elif(choice==3):
          mylist.insertFirst()
    elif(choice==4):
          mylist.insertMiddle()      
    elif(choice==5):
          mylist.insertLast()      
    elif(choice==6):
          mylist.deleteFirst()
    elif(choice==7):
          mylist.deleteMiddle()
    elif(choice==8):
          mylist.deleteLast()                              
    else:
         break