Subversion Repositories programming

// Written by Ira Snyder
// 11-03-2004
import java.io.*;
import java.util.*;

class UnorderedTree {
        private Object root;
        private Set subtrees;
        private int size;

        public UnorderedTree( ) { } //constructs an empty tree

        public UnorderedTree( Object root ) { //constructs a singleton
                this.root = root;
                subtrees = new HashSet(); //empty set
                size = 1;
        }

        //constructor to create any tree that is not a singleton
        //and is not an empty tree
        public UnorderedTree( Object root, Set trees ) {
                this(root);
                for( Iterator it=trees.iterator(); it.hasNext(); ) {
                        Object object = it.next();
                        if( object instanceof UnorderedTree ) {
                                UnorderedTree tree = (UnorderedTree)object;
                                subtrees.add(tree);
                                size += tree.size;
                        }
                }
        }

        public int size( ) { return size; }

        public void printPreOrder( PrintStream ps ) {
                printPreOrderHelper( ps, this ); //print the whole tree in preorder
                ps.println(); //end the line
        }

        public static void printPreOrderHelper( PrintStream ps, UnorderedTree tree ) {
                ps.print( tree.root + " " ); //print the node
                for( Iterator it=tree.subtrees.iterator(); it.hasNext(); ) {
                        //recurse subtrees in preorder
                        printPreOrderHelper( ps, (UnorderedTree)it.next() );
                }
        }

        public void printPostOrder( PrintStream ps ) {
                printPostOrderHelper( ps, this ); //print the whole tree in postorder
                ps.println(); //end the line
        }
        
        public static void printPostOrderHelper( PrintStream ps, UnorderedTree tree ) {
                for( Iterator it=tree.subtrees.iterator(); it.hasNext(); ) {
                        //recurse subtrees in postorder
                        printPostOrderHelper( ps, (UnorderedTree)it.next() );
                }
                ps.print( tree.root + " "); //print the node
        }

        public void printLevelOrder( PrintStream ps ) {
                Queue q = new Queue();

                q.enqueue(this); //add the root
                
                while( !q.isEmpty() ) {
                        //remove the first item in the queue
                        UnorderedTree temp = (UnorderedTree)q.dequeue();

                        ps.print(temp.root + " "); //visit the node

                        //add all the children of temp to the queue
                        for( Iterator it=temp.subtrees.iterator(); it.hasNext(); ) {
                                q.enqueue( it.next() );
                        }
                }
                ps.println(); //end the current line
        }

} //end class UnorderedTree