leetcode-Remove Linked List Elements

题目链接：

https://leetcode.com/problems/remove-linked-list-elements/

分析：

增加一个哑节点，可以简化删除节点是否是头节点的操作，具体实现代码如下图所示：

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(head == NULL)
        {
            return head;
        }
        ListNode dummy(-1);
        dummy.next = head;
        ListNode *cur = head;
        ListNode *pre = &dummy;
        while(cur != NULL)
        {
            ListNode *next = cur->next;
            if(cur->val == val)
            {
                pre->next = next;
                delete cur;
                cur = next;
            }
            else
            {
                pre = cur;
                cur = next;
            }
        }
        return dummy.next;
    }
};