反转一个单链表。
示例:
输入: 1->2->3->4->5->NULL 输出: 5->4->3->2->1->NULL
/** * 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* Pre=NULL, *Cur=head; while(Cur){ ListNode* Next = Cur->next; Cur->next = Pre; Pre = Cur; Cur = Next; } return Pre; } };