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(pHead == null) {
            return null;
        }
        int len = 0;
        ListNode p = pHead;
        while(p != null) {
            len++;
            p = p.next;
        }
        if(k > len) {
            return null;
        } else if(k == len) {
            return pHead;
        }
        int i = 0, t = len - k;
        p = pHead;
        while(i < t) {
            i++;
            p = p.next;
        }
        return p;
    }
}