移除链表元素

/**
 * 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) {
        ListNode* sentinel = new ListNode(0);
        sentinel->next = head;
        ListNode* pre,*cur;
        pre = sentinel;
        cur = sentinel->next;
        while(cur!=NULL)
        {
            if(cur->val == val)
            {
                pre->next = cur->next;
            }
            else
            pre = cur;
            cur = cur->next;
        }

        ListNode*ret = sentinel->next;
        return ret;
    }
};