题解 | 删除链表的节点-哨兵头结点

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param head ListNode类 
# @param val int整型 
# @return ListNode类
#
class Solution:
    def deleteNode(self , head: ListNode, val: int) -> ListNode:
        # write code her
        newhead=ListNode(-1)
        newhead.next=head
        cur=head
        pre=newhead
        while cur:
            if cur.val==val:
                pre.next=cur.next
                break
            pre=cur
            cur=cur.next
        return newhead.next