TowerStack

TowerStack

public class TowerStack<T:_Comparable> : Stack<T> {
    override func push(key:T) {
        let current:Node<T>! = top
        if (top == nil) {
            super.push(key)
        }
        else if (top.key! > key) {
            super.push(key)
        } else {
            NSException(name: "Tower Collapse", reason: "A larger disk is placed on top of a smaller disk", userInfo: nil).raise()
        }
    }
}