题目解析
举例说明：
'''链表反转'''
def reverse(head):prev = Nonecurrent = headwhile current:next_node = current.next # 临时保存下一个节点current.next = prev # 反转指针prev = current # prev 前移current = next_node # current 前移return prev # 返回新的头节点
举例说明：
'''链表反转'''
def reverse(head):prev = Nonecurrent = headwhile current:next_node = current.next # 临时保存下一个节点current.next = prev # 反转指针prev = current # prev 前移current = next_node # current 前移return prev # 返回新的头节点