Anonymous

     public void build ( ) throws IOException // Build tree from prefix expression
    {
        root = buildSub(makeNewNode());
    }




   private TreeNode buildSub ( TreeNode p )  throws IOException
    {
    	int x = (int)p.getElement();
    	if((p.getElement() == '*' ||p.getElement() == '/' ||p.getElement() == '+' ||p.getElement() == '-')){
    		System.out.println("calculator");
    			p.setLeft(buildSub(makeNewNode()));
    			p.setRight(buildSub(makeNewNode()));
    			return p;
    	}
    	else if(x >= 48 && x<=57){
    		System.out.println("number");
    		if(p.getLeft() == null){
    			p.setLeft(buildSub(makeNewNode()));
    		}
    		else{
    			p.setRight(buildSub(makeNewNode()));
    			return p;
    		}
    		
    	}
    	else{
    		System.out.println("incorrect");
    		return null;
    	}