思路:链表的删除 应该要建立一个虚拟节点
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* removeElements(ListNode* head, int val)
{
if(head==nullptr)
return head;
ListNode *dummy=new ListNode (0);
ListNode *cur=dummy;
dummy->next=head;
while(cur->next)
{
if(cur->next->val==val)
{
ListNode *delNode=cur->next;
cur->next=delNode->next;
delete delNode;
}
else
cur=cur->next;
}
return dummy->next;
}
};