def deleteNode(self, node: ListNode) -> None:
"""Do not return anything, modify node in-place instead.
Key: O(N), move the value one by one while traverse from node to tail.
"""
while node.next.next:
node.val = node.next.val
node = node.next
node.val = node.next.val
node.next = None
def deleteNode(self, node: ListNode) -> None:
"""Do not return anything, modify node in-place instead.
Key: O(1), move the value of node.next, and link from node to node.next.next.
The key is since we don't have prev, we modify this node as prev and instead delete node.next as node.
"""
node.val = node.next.val
node.next = node.next.next