In computer science, a stack is an abstract data type that serves as a collection of elements, with two principal operations:
- push, which adds an element to the collection, and
- pop, which removes the most recently added element that was not yet removed.
The order in which elements come off a stack gives rise to its
alternative name, LIFO (last in, first out). Additionally, a
peek operation may give access to the top without modifying
the stack. The name "stack" for this type of structure comes
from the analogy to a set of physical items stacked on top of
each other, which makes it easy to take an item off the top
of the stack, while getting to an item deeper in the stack
may require taking off multiple other items first
Simple representation of a stack runtime with push and pop operations.
push(elem) method
pop - Takes top element from the stack.
peek - Peeks at the top element of the stack.
size - Returns the size of the stack.