LintCode Python 简单级题目 452.删除链表中的元素

# 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 is None:
            return None
        # 可能链表中的所有元素val都等于val，所以需要新增一个头节点
        new = ListNode(0)
        new.next = head
        head = new
        pre = head
        # 遍历链表，删除等于val的所有节点
        while pre.next is not None:
            if pre.next.val == val:
                pre.next = pre.next.next
            else:
                pre = pre.next
        return new.next