删除链表中等于给定值val的所有节点（python实现）

Example：

Given 1->2->3->4->5->3, val = 3, return the list as 1->2->4->5

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

class Solution:
    # @param head, a ListNode
    # @param val, an integer
    # @return a ListNode
    def removeElements(self, head, val):
        # Write your code here
        if head == None:
            return head
        dummy = ListNode(0)
        dummy.next = head
        pre = dummy
        while head:
            if head.val == val:
                pre.next = head.next
                head = pre
            pre = head
            head = head.next
        return dummy.next