链表中倒数第k个结点

 1 /*
 2 public class ListNode {
 3     int val;
 4     ListNode next = null;
 5 
 6     ListNode(int val) {
 7         this.val = val;
 8     }
 9 }*/
10 public class Solution {
11     public ListNode FindKthToTail(ListNode head,int k) {
12         if(head==null||k<=0){
13             return null;
14         }
15         ListNode pre=head;
16         ListNode last=head;       
17         for(int i=1;i<k;i++){
18             if(pre.next!=null){
19                 pre=pre.next;
20             }else{
21                 return null;
22             }
23         }
24         while(pre.next!=null){
25             pre = pre.next;
26             last=last.next;
27         }
28         return last;
29     }
30 }