Poj Solution 1577

http://poj.org/problem?id=1577

//* @author: SmilingWang
import java.util.*;
public class Main {
  public static void main(String[] args){
   Scanner in =new Scanner(System.in);
   BinarySearchTree< Character> bt = new BinarySearchTree< Character>();
   boolean stop = false;
   while(true){
    String input = in.next();
            
    LinkedList< String> list = new LinkedList< String>();
    while(input.charAt(0) != '*'){
    if(input.charAt(0) == '$'){
      stop = true;
      break;
    }
    list.addFirst(input);
       input = in.next();
    }
            
    for(int i = 0; i < list.size(); i++){
      input = list.get(i);
      for(int j = 0; j < input.length(); j++){
       bt.insert((Character)input.charAt(j));
      }
    }
    bt.printTree();
    if(stop){
       return;
    }
    System.out.println();
    bt = new BinarySearchTree< Character>();
    }
  }
    
}

class BinaryNode< T extends Comparable< ? super T>> {
    BinaryNode< T> left;
    BinaryNode< T> right;
    T element;
    
    public BinaryNode(T theElement){
        this(theElement, null, null);
    }
    public BinaryNode(T theElement, BinaryNode<T> lt, BinaryNode<T> rt){
        element = theElement;
        left = lt;
        right = rt;
    }
    public T getElement(){
        return this.element;
    }
    public BinaryNode< T> getLeft(){
        return this.left;
    }
    public BinaryNode< T> getRight(){
        return this.right;
    }
    public String toString(){
        return element + "";
    }
}

class BinarySearchTree< T extends Comparable< ? super T>>{
    private BinaryNode< T> root;

    public BinarySearchTree(){
        root = null;
    }
    public BinarySearchTree(BinaryNode< T> t){
        root = t;
    }
    public void makeEmpty(){
        root = null;
    }
    public boolean isEmpty(){
        return root == null;
    }
    public T find(T x){
        return elementAt(find(x, root));
    }
    
    public void insert(T x){
        root = insert(x, root);
    }
    public void printTree(){
        printTree(root);
    }
    
    private T elementAt(BinaryNode< T> t){
        return t.element;
    }
    private BinaryNode< T> find(T x, BinaryNode< T> t){
        if(t == null){
            return null;
        }
        if(x.compareTo(t.element) < 0){
            return find(x, t.left);
        }
        else if(x.compareTo(t.element) == 0){
            return t;
        }
        else{
            return find(x, t.right);
        }
    }
    
    private BinaryNode< T> insert(T x, BinaryNode< T> t){
        if(t == null){
            t = new BinaryNode< T>(x, null, null);
        }
        else if(x.compareTo(t.element) < 0){
            t.left = insert(x, t.left);
        }
        else if(x.compareTo(t.element) > 0){
            t.right = insert(x, t.right);
        }
        else;
        return t;
    }
    private void printTree(BinaryNode< T> t){
        if(t != null){    
            System.out.print(t.element);
            printTree(t.left);
            printTree(t.right);
        }
    }
    
   
}