我的方法:迭代
class Solution { public ListNode reverseList(ListNode head) { if(head==null) return null; if(head.next==null) return head; ListNode pos=head.next; ListNode pos2=head; while(head.next!=null){ head.next=pos.next; pos.next=pos2; pos2=pos; pos=head.next; } return pos2; } }
第二种方法:递归
public ListNode reverseList(ListNode head) { if (head == null || head.next == null) return head; ListNode p = reverseList(head.next); head.next.next = head; head.next = null; return p; }