Python中链表的判断回文字符串的优化算法

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

def isPalindrome(head: ListNode) -> bool:
    stack = []
    slow = fast = head

    #使用快慢指针找到链表的中间节点
    while fast and fast.next:
        stack.append(slow.val)
        slow = slow.next
        fast = fast.next.next

    #处理链表长度为奇数的情况
    if fast:
        slow = slow.next

    #从链表头开始遍历链表，同时从栈顶弹出元素，比较它们的值是否相等
    while slow:
        if slow.val != stack.pop():
            return False
        slow = slow.next

    return True

#测试代码
head = ListNode('p')
head.next = ListNode('i')
head.next.next = ListNode('d')
head.next.next.next = ListNode('a')
head.next.next.next.next = ListNode('n')
head.next.next.next.next.next = ListNode('c')
head.next.next.next.next.next.next = ListNode('o')
head.next.next.next.next.next.next.next = ListNode('d')
print(isPalindrome(head)) #输出：True