单链表：在带头节点单链表中删除(minv, maxv)中的所有节点

struct node {
	int val;
	node *next;
};

void delInterval(node *head, int minx, int maxx) {
	if (!head) return head;
	node *pre = head;
	node *p = pre->next; //工作指针
	while (p) {
		if (minx < p->val && p->val < maxx) {
			//满足条件，p为待删除节点
			node *del = p;
			pre->next = p->next;
			p = p->next;
			delete del;
		} else {
			pre = pre->next;
			p = p->next;
		}
	}
	return head;
}