Stack

Stack

Structure with limited access to data.

L.I.F.O. ( Last In First Out ) Structure

How it works?

• You keep putting elements on top
• You have easy access to remove or look at the top element

When to use?

• when you only care about the most recent elements
• the order in which you see & save elements actually matters

Push & Pop

1. Push

   : when you add an element to a stack

   -> O(1)

2. Pop

   : when you taken an element off of the stack

   -> O(1)

=> All you need here is to look at the top element of the stack!

Stack in Python

• pop() is a given function
• append() is equivalent to a push function

Make your own code instead of using append() since it traverses the whole list, taking O(n)

-> it will take a lot faster if we push/pop from the first element in a linked list!