61. Rotate List
Given a list, rotate the list to the right by k places, where k is non-negative.
For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.
一开始读错题了， 想难了，其实很简单。
1 假设list长度为len ，快指针先走len-k步，
2.改变指向。
1 class Solution { 2 public ListNode rotateRight(ListNode head, int k) { 3 if(head==null) return head; 4 int len = 0; 5 for(ListNode p = head;p!=null;p=p.next) 6 len = len + 1; 7 k = k%len; 8 if(k==0) return head; 9 ListNode faster=head; 10 ListNode slower; 11 //find the node to rotate 12 for(int i = len - k;i > 1;i--) 13 faster = faster.next; 14 slower = faster; 15 // slower.next = null;//放在这里错误!!! 16 faster = faster.next; 17 slower.next = null;//放在这里正确！！！ 18 ListNode newhead = faster; 19 while(faster.next != null) 20 faster = faster.next; 21 faster.next = head; 22 return newhead; 23 24 } 25 26 }
ps:完全自己想出来的。