Hướng dẫn cấu trúc dữ liệu ngăn xếp Python

class Stack:
    def __init__(self):
        self.items = []
        
    def is_empty(self):
        return len(self.items) == 0
        
    def push(self, item):
        self.items.append(item)
        print(f"Pushed: {item}")
        
    def pop(self):
        if self.is_empty():
            return "Underflow: Stack is empty"
        popped = self.items.pop()
        print(f"Popped: {popped}")
        return popped
        
    def peek(self):
        if self.is_empty():
            return "Stack is empty"
        return self.items[-1]
        
    def size(self):
        return len(self.items)

# Initialize stack
stack = Stack()
stack.push("Apples")
stack.push("Bananas")
stack.push("Cherries")

print(f"Current Stack Size: {stack.size()}")
print(f"Top Element (Peek): {stack.peek()}")

stack.pop()
print(f"Stack after Pop: {stack.items}")

Pushed: Apples
Pushed: Bananas
Pushed: Cherries
Current Stack Size: 3
Top Element (Peek): Cherries
Popped: Cherries
Stack after Pop: ['Apples', 'Bananas']