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# 12.16 (Implement Stack using inheritance) In Listing 12.13, the Stack class is
# implemented using composition. Define a new Stack class using inheritance
# that extends list.
# Draw UML diagrams of the new class. Implement it. Write a test program that
# prompts the user to enter five strings and displays them in reverse order.
class Stack(list):
def __init__(self, size):
super().__init__()
self.size = size
self.counter = -1
def push(self, val):
if self.counter < self.size:
self.append(val)
self.counter += 1
else:
print("Stack is full!")
def pop(self):
if self.counter >= 0:
res = self[self.counter]
self[:] = self[:self.counter]
self.counter -= 1
return res
else:
return "Stack is empty"
def isEmpty(self):
return self.counter < 0
def peek(self):
if not self.isEmpty():
return self[self.counter]
else:
return "Stack is empty"
s = Stack(5)
s.push(10)
s.push(20)
s.push(30)
s.push(40)
s.push(50)
print(s.peek())
print(s.pop())
print(s.pop())
print(s.pop())
print(s.pop())
print(s.pop())
print(s.pop())
print(s.pop())
print(s.peek())
