My Recursive Java Solution
public ListNode deleteDuplicates(ListNode head) {\n        if (head == null) return null;\n        \n        if (head.next != null && head.val == head.next.val)
    public ListNode deleteDuplicates(ListNode head) {\n        if (head == null) return null;\n        \n        if (head.next != null && head.val == head.next.val) {\n            while (head.next != null && head.val == head.next.val) {\n                head = head.next;\n            }\n            return deleteDuplicates(head.next);\n        } else {\n            head.next = deleteDuplicates(head.next);\n        }\n        return head;\n    }\n    \n\n\nif current node is not unique, return deleteDuplicates with head.next. \nIf current node is unique, link it to the result of next list made by recursive call. Any improvement?
['Recursion']