LeetCode:Reverse Linked List

Reverse Linked List

Total Accepted: 60024 Total Submissions: 168196 Difficulty: Easy

Reverse a singly linked list.

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Hint:

A linked list can be reversed either iteratively or recursively. Could you implement both?

思路：头插法。

code:

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