LeetCode || Remove Linked List Elements

/** * 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* h = head;        ListNode* pre = NULL;        while(h!=NULL)//顺序查找，O(N)        {            if(h->val == val)            {                if(pre == NULL)                {                    head = head->next;                    pre = NULL;                }                else                {                    pre->next = h->next;                }            }            else            {                pre = h;            }             h = h->next;        }        return head;    }};