剑指 Offer 24. 反转链表

https://leetcode.cn/leetbook/read/illustration-of-algorithm/9pdjbm/

双指针

class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode *right = head, *left = NULL;
        while(right != NULL) {
            ListNode *tmp = right->next;
            right->next = left;
            left = right;
            right = tmp; 
        }
        return left;
    }
};