problem:
Reverse a singly linked list.
Hint:
A linked list can be reversed either iteratively or recursively. Could you implement both?
solution:头插法逆转链表
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
//头插法逆转链表
class Solution {
public:
ListNode* reverseList(ListNode* head) {
ListNode result(-1);
ListNode *cur=head;
while(cur!=NULL)
{
ListNode *nnode=new ListNode(cur->val);
nnode->next=result.next;
result.next=nnode;
cur=cur->next;
}
return result.next;
}
};