leetcode 203. Remove Linked List Elements

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;
    }
};