描述
计算链表中有多少个节点.
样例
样例 1: 输入: 1->3->5->null 输出: 3 样例解释: 返回链表中结点个数，也就是链表的长度. 样例 2: 输入: null 输出: 0 样例解释: 空链表长度为0
from lintcode import (
ListNode,
)
"""
Definition of ListNode:
class ListNode(object):
def __init__(self, val, next=None):
self.val = val
self.next = next
"""
class Solution:
"""
@param head: the first node of linked list.
@return: An integer
"""
def count_nodes(self, head: ListNode) -> int:
# write your code here
i = 0
while head is not None:
i += 1
head = head.next
return i
