高质量代码-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        
13         ListNode ans =  head;
14         
15         if (head == null || k < 1) {
16             return null;
17         }
18         int i = k;
19         //head先前进k-1个节点
20         while (i > 1 && head.next != null) {
21             head = head.next;
22             i--;
23         }
24         //节点总数不够
25         if (i != 1) {
26             return null;
27         }
28         
29         while (head.next != null) {
30             head = head.next;
31             ans = ans.next;
32         }
33        
34         return ans;
35         
36     }
37 }