在类方法中递归地反转链表

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

class Solution:
    def reverseList(self, head):
        # 递归终止条件：链表为空或只有一个节点
        if head is None or head.next is None:
            return head
        
        # 递归调用反转后的链表
        new_head = self.reverseList(head.next)
        
        # 反转当前节点的指针
        head.next.next = head
        head.next = None
        
        return new_head