LeetCode之Reverse Linked List

 /*链表的头插法。*/
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if(head == nullptr || head->next == nullptr) return head;
        ListNode node(-1);
        node.next = head;
        head = head->next;
        node.next->next = nullptr;
        while(head != nullptr){
            ListNode *p = head;
            head = head->next;
            p->next = node.next;
            node.next = p;
        }
        return node.next;
    }
};