力扣（LeetCode) -移除链表元素（C语言）

删除链表中等于给定值 val 的所有节点。

示例:

输入: 1->2->6->3->4->5->6, val = 6
输出: 1->2->3->4->5

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */


struct ListNode* removeElements(struct ListNode* head, int val){
    struct ListNode *head_pre = (struct ListNode *)malloc(sizeof(struct ListNode));
    head_pre->next = head;
    struct ListNode *p = head_pre;
    while (p && p->next)
    {
        while (p->next && p->next->val == val)
        {
            if (p->next ==  head) 
                head = head->next;
            else
                p->next = p->next->next;
        }
         p = p->next;
    }
    return head;
}