206. Reverse Linked List

1.描述

Reverse a singly linked list.

2.分析

3.代码

/**
 * 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 || head->next == NULL) return head;
        ListNode* cur = head;
        ListNode* pre;
        head = NULL;
        while (cur != NULL) {
            pre = cur;
            cur = cur->next;
            pre->next = head;
            head = pre;
        }
        return head;        
    }
};