Question

All code should be in Python 3. Implement the Stack Class, using the push, pop, str, init methods, and the insurance variable 'list'.

Answer 1

We can't use list as a variable a it is a predefined function in python. So, it will show error.

---------------------Program-----------------

import random

class Stack():

    # constructor

    def __init__(self):

   

        self._elements = []

        self._count = 0

    # push elt into the stack

    def push(self, elt):

   

        self._elements.append(elt)

       

        self._count += 1

    # pop top most element from the stack

    def pop(self):

   

        # if stack is empty

        if self.is_empty():

            return 'Stack Empty!'

       

        # decrement the count of elements in the stack

        self._count -= 1

       

        # return the top most element in th list

        return self._elements.pop()

    # get the top most element from the stack

    def top(self):

   

        if self.is_empty():

            return 'Stack Empty!'

        else:

            return self._elements[self._count - 1]

       

    # return true if the stack is empty, false otherwise

    def is_empty(self):

   

        return self._count == 0

    # get the size of stack

    def size(self):

   

        return self._count

    def __str__(self):

       

        # if stack is empty

        if self.is_empty() == True:

            return '()'

       

        ans = '('

       

        for i in range(0, self._count - 1):

       

            ans += str(self._elements[i]) + ', '

           

        ans += str(self._elements[self._count - 1]) + ')'

       

        return ans

    def __repr__(self):

   

        if self.is_empty() == True:

            return 'Stack List ()'

   

        ans = 'Stack List ('

        

        for i in range(0, self._count - 1):

       

            ans += str(self._elements[i]) + ', '

           

        ans += str(self._elements[self._count - 1]) + ')'

       

       return ans

       

s = Stack()

s.push(random.randint(-100, 100))

s.push(random.randint(-100, 100))

s.push(random.randint(-100, 100))

s.push(random.randint(-100, 100))

print(s)

print(s.__repr__())

print('\nTop Most Element :', s.top())

print('\nPopping Stack ...')

while not s.is_empty():

    print(s.pop())

Sample Output