We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Prepare
  2. Data Structures
  3. Linked Lists
  4. Reverse a doubly linked list
  5. Discussions

Reverse a doubly linked list

  • emhhacker
     + 0 comments

    My Java solution with linear time complexity and constant space complexity:

     public static DoublyLinkedListNode reverse(DoublyLinkedListNode llist) {
        //return llist if its null, indicating the llist is empty
        if(llist == null) return llist;
        
        //use a curr ptr
        DoublyLinkedListNode curr = llist;
        
        //iterate thru the llist
        while(curr != null){
            //store curr nxt in a temp var
            DoublyLinkedListNode temp = curr.next;
            curr.next = curr.prev;
            curr.prev = temp;
            
            if(temp == null) break;
            else curr = temp;
        }
        return curr;        
    }