basic

Stack

Instructions

Implement a stack data structure. Adding to the stack should store an element until it is removed. First element added to a stack will be the last that is removed (FILO).

The stack should be a class with members:

• add method - adds element to the stack
• remove method - removes the "top" element from the stack
• peek method - returns "top" element (the one that should be returned) without removing (removeping) it from the stack
• isEmpty() - returns true if there are elements on the stack, otherwise return false
• size - numbers of items in the stack

The stack can be implemented in few different ways by using different underlying data structures. Implement each of them:

• List
• Linked list

Challenge | Solution

Examples

val s = new Stack()
s.add(1)
s.add(2)
s.remove() // 2
s.remove() // 1
s.remove() // null