ImperfectPalendrome.swift

import Foundation

var stack = [Character]()

func isPalendrome(subject: String) -> Bool {
    var reversed = ""
    var sanitized = ""

    for character in subject where character.isLetter {
        sanitized.append(character)
        stack.append(character)
    }

    while stack.isEmpty == false {
        reversed.append(stack.removeLast())
    }

    return reversed == sanitized
}

print(isPalendrome(subject: "a man a plan a canal panama"))