[LeetCode笔记]-203-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* newHead = new ListNode(36);
        newHead->next = head;
        ListNode* pre =  newHead;
        ListNode* cur =  head;
        while(cur!=NULL)
        {
            if(cur->val == val)
            {
                cur = cur->next;
                pre->next = cur;
            }
            else
            {
                cur = cur->next;
                pre = pre->next;
            }
        }
        return newHead->next;
    }
};

/**
 * 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==NULL) 
           return NULL;
        head->next = removeElements(head->next, val);
        return head->val == val ? head->next : head;
    }
};