CCI 2.2 找出单向链表中倒数第k个结点

实现一个算法，找出单向链表中倒数第k个结点。

package test;

public class KthNode {
//快慢指针
public Node kthNode(Node head, int k){
if(head==null || k<=0)
return null;
Node slow, fast;
slow = fast = head;
while(k>0){
if(fast==null)
return null;
fast = fast.next;
k--;
}
while(fast != null){
fast = fast.next;
slow = slow.next;
}
return slow;
}
}