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
        // List<ListNode> List = new ArrayList<>();
        // ListNode curr = pHead;
        // while(curr != null){
        //     List.add(curr);
        //     curr = curr.next;
        // }
        // if( k == 0 || k > List.size()){
        //     return null;
        // }

        // return List.get(List.size() - k);

        ListNode curr = pHead;
        int count = 0;
        while(curr != null){
            curr = curr.next;
            count ++;
        }
        if(k > count){
            return null;
        }
        curr = pHead;
        for(int i = 0; i < count - k; i++){
            curr = curr.next;
        }
        return curr;

    }
}