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) {
        // write code here
        ListNode* newNode = nullptr;
        while (head != nullptr) {
            int temp_val = head->val;
            if (newNode == nullptr) {
                newNode = new ListNode(temp_val);
                newNode->next = nullptr;
            }
            else {
                ListNode* temp = new ListNode(temp_val);
                temp->next = newNode;
                newNode = temp;
            }
            head = head->next;
        }
        return newNode;
    }
};