LeetCode 206. Reverse Linked List（C++版）

Reverse a singly linked list.反转单链表。

非递归版本：

/** * 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) {        ListNode *newhead  = NULL;                while(head){            ListNode *nextNode = head -> next;            head -> next = newhead;            newhead = head;            head = nextNode;        }                return newhead;    }};

递归版本：

class Solution {public:     ListNode * reverseListIter(ListNode * head, ListNode * newhead){        if(head == NULL) return newhead;                ListNode * nextnode = head -> next;        head -> next = newhead;        return reverseListIter(nextnode, head);    }    ListNode * reverseList(ListNode *head){        return reverseListIter(head, NULL);    }};