题解 | #链表中倒数最后k个结点#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pHead ListNode类 
     * @param k int整型 
     * @return ListNode类
     */
    public ListNode FindKthToTail (ListNode pHead, int k) {
        // write code here
        if(k == 0){return null;}
        Deque<ListNode> queue = new LinkedList<>();
        ListNode cur = pHead;
        while(cur!=null){
            if(queue.size()<k){
                queue.addLast(cur);
            }else{
                if(queue.size()!=0){
                    queue.removeFirst();
                }
                
                queue.addLast(cur);
            }
            cur = cur.next;
        }
        if(queue.size()<k){
            return null;
        }else{
            return queue.getFirst();
        }
    }
}