Remove_Linked_List_Elements.md

203. Remove Linked List Elements

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

Method:

# 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
        """
        dummy=ListNode(0)
        h, prev=head, dummy
        dummy.next=head
        while h:
            while h and h.val!=val:
                prev=h
                h=h.next
            while h and h.val==val:
                h=h.next
            prev.next=h
        return dummy.next

或者：

# 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
        """
        dummy=ListNode(0)
        dummy.next=head
        cur, prev=head, dummy
        while cur:
            if cur.val==val:
                cur=cur.next
                prev.next=cur
            else:
                cur=cur.next
                prev=prev.next
        return dummy.next