day32.java

Q1: https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/description/
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode prev = dummy;
        ListNode curr = head;
        
        while (curr != null) {
            if (curr.next != null && curr.val == curr.next.val) {
                while (curr.next != null && curr.val == curr.next.val) {
                    curr = curr.next;
                }
                prev.next = curr.next;
            } else {
                prev = prev.next;
            }
            curr = curr.next;
        }
        
        return dummy.next;
    }
}
TC-O(N)
SC-O(1)