【剑指offer】输出链表倒数第K个元素

 /*
 public class ListNode {
     int val;
     ListNode next = null;

     ListNode(int val) {
         this.val = val;
     }
 }*/
 public class Solution {
     public ListNode FindKthToTail(ListNode head,int k) {
         if(head == null) return null;
         int length = 0;
         ListNode tempNode = head;
         ListNode result;
         while(tempNode!=null){
             length++;
             tempNode = tempNode.next;
         }
         //判断K值是否合法
         if(k > length) return null;
         tempNode = head;
         for(int i=0; i<length; i++){
             if(i>=k){
                 head = head.next;
             }
             tempNode  = tempNode.next;
         }
         return head;
     }
 }