题解 | #链表中倒数最后k个结点#

import java.util.*;
public class Solution {
    public ListNode FindKthToTail (ListNode pHead, int k) { 
        int n = 0;
        ListNode fast = pHead;
        ListNode slow = pHead;
        //快指针先行k步 fast-template
        for(int i = 0; i < k; i++){
            if(fast != null)
                fast = fast.next;
            //达不到k步说明链表过短，没有倒数k
            else
                return slow = null;
        }
        //快慢指针同步，快指针先到底，慢指针指向倒数第k个
        while(fast != null){
            fast = fast.next;
            slow = slow.next;
        }
        return slow;
    }
}