迭代实现：
def reverse_linked_list_iteration(node):
if not node:
return node
pre_node = None
while node.next:
next = node.next
node.next = pre_node
pre_node = node
node = next
node.next = pre_node
return node
递归实现：
def reverse_linked_list_recursion(node):
if not node or not node.next:
return node
new_head = reverse_linked_list_recursion(node.next)
node.next.next = node
node.next = None
return new_head