https://leetcode.com/problems/remove-duplicates-from-sorted-list/description/

public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null){
            return head;
        }
        ListNode curr = head;

        while(curr.next != null){
            if(curr.val == curr.next.val){
                curr.next = curr.next.next;
            }
            else{
                curr = curr.next;
            }
        }
        if(curr.val == head.val){
            head.next = null;
        }
        return head;
    }