203. 移除链表元素

题目描述

删除链表中等于给定值 val 的所有节点。

示例:

输入: 1->2->6->3->4->5->6, val = 6
输出: 1->2->3->4->5

我的解法——pre指针（AC）

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

class Solution(object):
    def removeElements(self, head, val):
        """
        :type head: ListNode
        :type val: int
        :rtype: ListNode
        """
        
        pre = head
        while(pre):
            if(pre.val == val):
                pre = pre.next
            else:
                break
        head = pre
        
        if(not head):
            return head
        now = pre.next
 
        while(now):
            if(now.val == val):
                now = now.next
                pre.next = now
            else:
                pre = pre.next
                now = now.next
                
        return head