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
        ListNode lenp = pHead;
        int pos = getLen(lenp) - k;
        if(pos < 0){
            return null;
        }
        if(pos == 0){
            return pHead;
        }
        while (pHead != null) {
            pos --;
            if (pos != 0) {
                pHead = pHead.next;
                continue;
            }
            return pHead.next;
        }
        return null;
    }

    public int getLen(ListNode ph) {
        int i = 0 ;
        while (ph != null) {
            i++;
            ph = ph.next;
        }
        return i;
    }
}