LinkedStack.py

class Node:

    def __init__(self,data):
        self.data=data
        self.next=None

class Stack:

    def __init__(self):
        self.head=None

    def is_empty(self):
        if self.head == None:
            return True
        else:
            return False

    def push(self,data):
        if self.head == None:
            self.head = Node(data)
        else:
            new_node=Node(data)
            new_node.next = self.head
            self.head=new_node

    def pop(self):
        if self.is_empty():
            return None
        else:
            popped_node=self.head
            self.head=self.head.next
            popped_node.next=None
            return popped_node.data

    def peek(self):
        if self.is_empty():
            return None
        else:
            return self.head.data

        
    def display(self):
        iternode=self.head
        if self.is_empty():
            print("Stack Undeflow")
        else:
            while iternode != None:
               print(iternode.data,end=" ")
               iternode=iternode.next
               if iternode != None:
                   print("->",end=" ")
            return      
            
if __name__=="__main__":
    MyStack=Stack()
    MyStack.push(11)
    MyStack.push(22)
    MyStack.push(33)       
    MyStack.push(44)

    MyStack.display()

    print("\n Top element is ",MyStack.peek())

    MyStack.pop()
    MyStack.pop()
    MyStack.display()

    print("\n Top element is ",MyStack.peek())