I am not sure why my solution fails to linked list question fail. My initial thought was to use two pointers along with a dummy node. The p1 start at dummy node while p2 starts at the head; they both iterate until they find a duplicate node and remove it from the list. The error message shows it still shows process exited with signal SIGILL. How do I resolve this?
func deleteDuplicates(_ head: ListNode?) -> ListNode? {
var dummyNode = ListNode(0, head)
var p1: ListNode? = dummyNode
var p2 = head
while p1 != nil && p2 != nil{
if p1!.val != p2!.val {
p1 = p1!.next
p2 = p2!.next
}
else if p1!.val == p2!.val{
p2!.next = p2?.next!.next
}
}
return p2
}