代码随想录：反转链表

代码随想录：反转链表

头插法

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode* virt = new ListNode();
        ListNode* target = head;
        while (target != NULL) {
            ListNode* temp = target->next;
            target->next = virt->next;
            virt->next = target;
            target = temp;
        }

        return virt->next;
    }
};