题解 | 反转链表

/**
 * struct ListNode {
 *  int val;
 *  struct ListNode *next;
 *  ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
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) {
        // write code here
        ListNode* prev = nullptr, *cur = head, *tmp = nullptr;

        while (cur) {
            tmp = cur;
            cur = cur->next;
            tmp->next = prev;
            prev = tmp;
        }

        return prev;
    }
};