题解 | #反转链表#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* ReverseList(ListNode* head) {
        if(head == nullptr)
            return head;
        ListNode* dummy = head;
        ListNode* left = head;
        ListNode* right = head->next;
        while(right != nullptr) {
            ListNode* next = right->next;
            right->next = left;
            left = right;
            right = next;
        }
        dummy->next = nullptr;
        return left;
    }
};

引入虚拟节点解决问题