ArrayDeque Performance Results

Herman van Hövell tot Westerflier replaced the Stack used in the iterative code with an ArrayDeque, introduced in Java 6. As many people, including Herman, have pointed out, Stack is a synchronized data structure and, as such, will incur an unnecessary performance penalty. Herman's results are posted below. The main result is that the fast iterative version comes within roughly 130% of the hardcore version, representing a significant tightening compared to the Stack.