Remove all elements from a linked list of integers that have value val.

Example
Given: 1 –> 2 –> 6 –> 3 –> 4 –> 5 –> 6, val = 6
Return: 1 –> 2 –> 3 –> 4 –> 5

思路

简单的链表删除操作。

一定要搞清楚边界条件：如果删除第一个或者最后一个元素会怎么样。然后问题就迎刃而解了。

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# 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
        """
        if (head):
            cur = head
            while (cur):
                if (cur.val == val):
                    if (cur.next):
                        head = cur.next
                    else:
                        head = None
                    cur = head
                else:
                    break
            if (cur):   
                while (cur.next is not None):
                    if (cur.next.val == val):
                        cur.next = cur.next.next
                    else:
                        cur = cur.next
                
        return head