CircularLinkedList.py

class _Node:
    __slots__ = '_element','_next'
    
    def __init__(self, element, next):
        self._element = element
        self._next = next
        
class CircularLL:
    def __init__(self):
        self._head = None
        self._tail = None
        self._size = 0
        
    def __len__(self):
        return self._size
        
    def isempty(self):
        return self._size == 0
        
    def addlast(self, e):
        newest = _Node(e,None)
        if self.isempty():
            newest._next = newest
            self._head = newest
        else:
            newest._next = self._tail._next
            self._tail._next = newest
        
        self._tail = newest    
        self._size +=1
        
    def addfirst(self,e):
        newest = _Node(e, None)
        if self.isempty():
            newest._next = newest
            newest._head = newest
            newest._tail = newest
        
        else:
            self._tail._next = newest
            newest._next = self._head
            
        self._head = newest
        self._size += 1
    
    def addany(self, e, position):
        newest = _Node(e,None)
        p = self._head
        i = 1 
        while i < position - 1:
            p = p._next
            i = i+1 
            
        newest._next = p._next
        p._next = newest
        self._size += 1
        
    def removefirst(self):
        if self.isempty():
            print("List is Empty")
            return
        e=self._head._element #retrival
        
        self._tail._next = self._head._next
        self._head = self._head._next 
        
        self._size -=1
        
        if self.isempty():
            self._head = None
            self._tail = None
        return e
        
    def removelast(self):
        if self.isempty():
            print("Empty")
            return
        
        p = self._head
        i = 1
        while i < len(self):
            p = p._next
            i =i + 1 
        self._tail = p 
        p = p._next
        self._tail._next = self._head
        e = p._element
        self._size -= 1 
        return e 
        
    def removeany(self,position):
        p = self._head
        i = 1 
        while i < position - 1:
            p = p._next
            i = i+1 
        e = p._next._element
        p._next = p._next._next
        self._size -= 1 
        return e 
        
        
    def display(self):
        p = self._head
        i = 0 
        while i < len(self):
            print(p._element,end='-->')
            p = p._next
            i = i+1 
        print()
            
C = CircularLL()
C.addlast(7)
C.addlast(4)
C.addlast(12)
C.display()
print("Size : ", len(C))
print()

C.addfirst(20)
C.display()
print("Size : ", len(C))
print()

C.addany(40,3)
C.display()
print("Size : ", len(C))
print()

C.removefirst()
C.display()
print("Size : ", len(C))
print()

C.removelast()
C.display()
print("Size : ", len(C))
print()

C.removeany(2)
C.display()
print("Size : ", len(C))