Chapter 22 Binary Trees, AVL Trees, and Priority Queues ritten before their operands. 4. Prefix Calculator An arithmetic expression is in prefix form when operators are written before their, Here are some examples of prefix expressions and the values they evaluate to: Value VideoNote Prefix Iculator Expression 12 53 +2 51 * 5 7 80 * + 16 4 + 3 1 An expression (such as 12) that begins with an integer is a prefix expression that evaluates to itself. Otherwise, an expression is a prefix expression if it begins with an operator and is followed by two prefix expressions. In this latter case, the value of the expression is recur- sively computed from the values of its constituent prefix sub-expressions. Write a program that allows the user to enter prefix expressions in a text field. The program reads the expression, evaluates it, and displays the value in a suitable GUI component. Assume that the user enters expressions that use only positive integers and the two opera- tors + and *. Your program should internally convert the prefix expression into a binary tree before evaluating it