Q:
Reverse a singly linked list.
Example:
Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL
Follow up:
A linked list can be reversed either iteratively or recursively. Could you implement both?
A:
/*** 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 oldPre(0); oldPre.next = head; ListNode newPre(0); while(oldPre.next) { auto tmp = oldPre.next; oldPre.next = tmp->next; tmp->next = newPre.next; newPre.next = tmp; } return newPre.next; } };**********Mistakes*************
ListNode *oldPre(0); ---------> this grammar is WRONG