LeetCode:203.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* cur=head;
        if(head==NULL)
        {
            return head;
        }

        while(head&&head->val==val)//这里要判断头结点不为空否则可能会导致访问空指针
        {
            head=head->next;
        }

        while(cur->next!=NULL)
        {
            if(cur->next->val==val)
            {
                //删除cur->next
                ListNode* delNode=cur->next;
                cur->next=delNode->next;
                delete delNode;
            }
            else
            {
                cur=cur->next;
            }
        }
        return head;
    }
};