reverseTheDLL

    //function to revrese the dll 
    public DLL reverseTheDLL(){
        //i use  tmp as current pointer
        DLLNode<T> tmp=tail;
 
        DLL<T> rev = new DLL<>(); 
        //checking if its not empty 
        while(tmp!=null){
            //adding tmp.info to the new DLL at head postion
            rev.addToHead(tmp.info);
            //we need so we can traverse
            tmp=tmp.prev;
        }
       return rev;
    }
    
    public void reverseTheDLL2(){
        //i use  tmp as current pointer
        DLLNode<T> tmp,placeholder=null;
        //starting at tail
        tmp=tail;
        while(tmp!=null){
            //store .prev
            placeholder=tmp.prev;
            tmp.prev=tmp.next;
            tmp.next=placeholder;
            //since tmp.next  now point at  prev we use it to traverse
            tmp=tmp.next;
        }
        placeholder=tail;
        tail=head;
        head = placeholder;
       
    }