leetcode-203-remove linked list elements

Remove all elements from a linked list of integers that have value val.

Example
Given: 1 –> 2 –> 6 –> 3 –> 4 –> 5 –> 6, val = 6
Return: 1 –> 2 –> 3 –> 4 –> 5

去掉单向链表中所有值与给定值相等的结点。

保存之前的结点，然后扫描每个节点即可。注意头结点是否会被去掉的问题。

/**
 * 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) return head;
        ListNode * prev = head;
        ListNode * cur = prev->next;
        while(prev->next)
        {
            if(cur->val == val){
                prev->next =  cur->next;
                cur=prev->next;
            }else{
                prev= cur;
                cur = prev->next;
            }
        }
       if(head->val == val) return head->next;
       return head;
    }
};