import java.util.*; public class Node { private String name; private Node firstChild; private Node nextSibling; Node (String n, Node d, Node r) { // TODO!!! Your constructor here } public static Node parsePostfix (String s) { return null; // TODO!!! return the root } public String leftParentheticRepresentation() { return ""; // TODO!!! return the string without spaces } public static void main (String[] param) { String s = "(B1,C)A"; Node t = Node.parsePostfix (s); String v = t.leftParentheticRepresentation(); System.out.println (s + " ==> " + v); // (B1,C)A ==> A(B1,C) } }