LeetCode: Reverse Linked List

Reverse a singly linked list.

源代码１：

/** * 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) {                vector<int> v;        struct ListNode* tmp = head;        while(tmp != NULL ) {            v.push_back(tmp->val);            // struct ListNode* t = tmp->next;            tmp = tmp->next;        }                int len = v.size();        tmp = head;        for (int i = 0; i < len ;++i) {            tmp->val = v[len - i - 1];            tmp = tmp->next;        }                return head;            }};

源代码２：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     struct ListNode *next; * }; */struct ListNode* reverseList(struct ListNode* head) {        struct ListNode* tmp1 = head;    struct ListNode* tmp2;    struct ListNode* tmp3;        if (tmp1 != NULL) {        tmp2 = tmp1->next;    }    else return tmp1;    while(tmp2 != NULL) {                tmp3 = tmp2->next;        tmp2->next = tmp1;        tmp1 = tmp2;        tmp2 = tmp3;    }    head->next = NULL;        return tmp1;            }