Reverse a singly linked list.
/**
* 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 || !(head->next)) return head;
ListNode* p=head->next;
ListNode* ln=reverseList(head->next);
p->next=head;
head->next=NULL;
return ln;
}
};
之前错误:
把p->next=head; 写成 ln->next=head;
ln是返回链表的头指针