力扣 234. 回文链表

前置

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

递归

def isPalindrome(head):
    def digui(s, e):
        if not e: return s, True
        s, ret = digui(s, e.next)
        ret = ret and s.val == e.val
        return s.next, ret
    _, ret = digui(head, head)
    return ret