Interface Queue<E> FIFO (First In First Out)
LinkedList (java.util.LinkedList)
Class Stack<E> LIFO (Last In First Out)
Convert Infix to Postfix Using Stack
Infix to Postfix Conversion
Infix to Postfix Conversion - https://eecs.wsu.edu/~nroy/courses/cpts122/labs/Infix2Postfix.pdf
Evaluate Postfix Expressions Using Stack