     var stack = Stacky<Character>(items: Array(word.characters))
     var reverseStack = Stacky<Character>(items: Array(word.characters).reverse())
     
-    for _ in 0..<stack.count() {
-        if stack.pop() != reverseStack.pop() {
+    for _ in 0..<stack.count() { // O(n)
+        if stack.pop() != reverseStack.pop() { // O(1)
             return false
         }
     }

addValues(arr2)


// create function that determines n power of n
func powerOfN(number: Int, power: Int) -> Int {
    var sum = 1
    
    if power == 0 {
        return 1
    }
    

    
//    numbers = numbers.sort() // 1) if we can use a sort function: O(n log n)
//    numbers.minElement() // 2) or just ask for min element: O(n)
//    let minNum = numbers.reduce(Int.max, combine: { min($0, $1) }) // 3) or use reduce
    
    for i in 0...numbers.count-1 {
        for j in 0...numbers.count-1 { // O(n^2)
