[Swift] Stack

import Foundation struct Stack { var stack: [Int] = [] mutating func push(x: Int) { stack.append(x) } mutating func pop() -> Int { return stack.isEmpty ? -1 : stack.removeLast() } func size() -> Int { return stack.count } func empty() -> Int { return stack.isEmpty ?

1 : 0 } func top() -> Int { return stack.last ?? -1 } } let n = Int(readLine()!)!

var stack = Stack() for _ in 0..
split(separator: " ") switch line[0] { case "push" : stack.push(x: Int(line[1])!) case "pop...