Stack

Description

Stacks are an abstract data type (ADT) that function to store and manipulate data. Their order is last-in-first-out (LIFO). To implement a stack, an array or linked list can be used. A stack is similar to a Tower of Hanoi in that the first object pushed onto the stack cannot be removed until every other object pushed on top of it has also been removed. It is also similar to a stack of plates in a cafeteria, where the bottom plate cannot be removed until all of the plates above it have been removed as well.

Functions

• Pop() --Removes an item from the stack
• Push() --Adds an item to the stack
• Peek() --Returns the top element of the stack
• isEmpty() --Returns true if the stack is empty

Time Complexity

All the functions are O(1).