[LeetCode]Reverse Linked List

题目描述：(链接)

Reverse a singly linked list.

解题思路:

链表真讨厌，总是出错。头插法。

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if (head == NULL ) return head;
        
        ListNode dummy(-1);
        dummy.next = head;
        
        ListNode *prev = dummy.next;
        ListNode *cur = prev->next;
        while (cur != NULL) {
            prev->next = cur->next;
            cur->next = dummy.next;
            dummy.next = cur;
            cur = prev->next;
        }
        
        return dummy.next;
    }
};