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 
12 
13 public ListNode FindKthToTail(ListNode head,int k) {
14         if(head==null||k<=0){
15             return null;
16         }
17         ListNode pre=head;
18         ListNode last=head;       
19         for(int i=1;i<k;i++){
20             if(pre.next!=null){
21                 pre=pre.next;
22             }else{
23                 return null;
24             }
25         }
26         while(pre.next!=null){
27             pre = pre.next;
28             last=last.next;
29         }
30         return last;
31     }
32 }