题解 | #链表中倒数最后k个结点#

using System;
using System.Collections.Generic;

/*
public class ListNode
{
    public int val;
    public ListNode next;

    public ListNode (int x)
    {
        val = x;
    }
}
*/

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 static int Len(ListNode phead) {
        if (phead == null) return 0;
        ListNode t = phead;
        int len = 1;
        while (t.next != null) {
            t = t.next;
            ++len;
        }
        return len;
    }
    public ListNode FindKthToTail(ListNode pHead, int k) {
        // write code here
        int len = Len(pHead);
        if ( len < k) return null;
        ListNode res = pHead;
        for (int i = 1; i <= len - k; i++) {
            res = res.next;
        }
        return res;
    }
}