//: FROM https://www.anuomob.com
import UIKit
struct Stack<Element> {
var items = [Element]()
mutating func push(_ item:Element){
items.append(item)
}
mutating func pop() ->Element?{
if(items.count > 0){
return items.removeLast()
}
return nil
}
}
var stackOfStrings = Stack<String>()
stackOfStrings.push("1234")
stackOfStrings.push("2234")
stackOfStrings.items
stackOfStrings.pop()
stackOfStrings.items
stackOfStrings.pop()
stackOfStrings.items
stackOfStrings.pop()
stackOfStrings.items
扩展
extension Stack{
var topElement : Element? {
return items.isEmpty ? nil : items[items.count-1]
}
}
stackOfStrings.push("22341")
stackOfStrings.push("22342")
stackOfStrings.topElement