Stacks

Stack

• A Stack is a special linear data structure that only allows insertion and deletion operations at one end of the structure.
• This end is called the Top, and the other end is called the Bottom.
• Stack operations follow the Last-In, First-Out (LIFO) principle.

Push

Add a new element at the top of the stack.

Pop

Remove and return the element at the top of the stack.

Top (Peek)

Return the element at the top of the stack without removing it.

Using a List to Simulate a Stack

Python’s list provides all the necessary operations to easily simulate a stack.

• Push: Use the list’s append() method
• Pop: Use the list’s pop() method (without arguments)
• Top: Access the last element of the list with stack[-1]
• Check if the stack is empty: Check the length of the list with len(stack) == 0, or simply use if not stack