删除链表的节点

给定单向链表的头指针和一个要删除的节点的值，定义一个函数删除该节点。
返回删除后的链表的头节点。
LeetCode链接：https://leetcode-cn.com/problems/shan-chu-lian-biao-de-jie-dian-lcof/

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    def deleteNode(self, head: ListNode, val: int) -> ListNode:

        now = head
        last = None
        while now is not None and now.val != val:
            last = now
            now = now.next
            

        if now is None:
            return None

        if last is None:
            head = head.next
            return head