1def deleteDuplicates(head):
2 dummy = ListNode(0, head)
3 prev = dummy
4 curr = head
5
6 while curr:
7 if curr.next and curr.val == curr.next.val:
8 # Skip all duplicates
9 while curr and curr.val == prev.next.val:
10 curr = curr.next
11 prev.next = curr
12 else:
13 prev = curr
14 curr = curr.next
15
16 return dummy.next