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
        int length = 0;
        ListNode cur = pHead;
        ListNode cur2 = pHead;
        if(pHead == null){
            return null;
        } else {
            while(cur != null){
                length++;
                cur = cur.next;
            }
            if(length == k){
                return pHead;
            } else if(length < k){
                return null;
            } else{
                k = length - k;
                for(int i = 0;i<k;i++){
                    cur2 = cur2.next;
                }
                return cur2;
            }
        }
    }
}