Stack

What is a Stack? A stack is an abstract data type that serves as a collection of elements and implements operations like push, pop, and peek at the end in O(1) time. It uses the LIFO (last in, first out) order. For example, a stack can be a collection of items where adding or removing is practical at the top. Code Example struct Stack<Element> { private var array: [Element] init(array: [Element] = []) { self.array = array } mutating func push(_ element: Element) { array.append(element) } mutating func pop() -> Element? { if array.isEmpty { return nil } return array.popLast() } func peek() -> Element? { if array.isEmpty { return nil } return array.last } } Practical Applications of Stacks You can observe stack-like behavior in many places, such as redo-undo features in text editors, Photoshop, and the forward and backward navigation features in web browsers. ...