203. Remove Linked List Elements 删除链表中val

203. Remove Linked List Elements

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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

/**
 * 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 *pre = new ListNode(-1), *cur = pre;
        pre->next = head;
        while (cur->next != nullptr) {
            if (cur->next->val == val) {
                ListNode *t = cur->next;
                cur->next = cur->next->next;
                t->next = nullptr;
                delete t;
            } else {
                cur = cur->next;
            }
        }
        return pre->next;
    }
};