逆置链表（原地逆置链表）

方法一：迭代递推

//带哨兵位
void reverse1(LinkList* phead) {
	LinkList* pre = phead->next, * nex = NULL;
	phead->next = NULL;
	while (pre != NULL) {
		nex = pre->next;
		pre->next = phead->next;
		phead->next = pre;
		pre = nex;
	}
}
//不带哨兵位
void reverse2(LinkList** phead) {
	LinkList* pre = NULL, * nex = NULL;
	while ((*phead) != NULL) {
		nex = (*phead)->next;
		(*phead)->next = pre;
		pre = (*phead);
		(*phead) = nex;
	}
	(*phead) = pre;
}

方法二：遍历原链表，头插新链表（过于无脑）

    struct ListNode* newhead = NULL;
    struct ListNode* cur = head;
    while(cur!=NULL){
        struct ListNode* nextN = cur->next;
        cur->next = newhead;
        newhead = cur;
        cur = nextN;
    }
    return newhead;