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;
        ListNode fast, slow;
        fast = pHead;
        slow = pHead;
        int n=1;
        while(fast.next!=null){
            fast = fast.next;
            n = n+1;
        }
        if(n-k<0) return null;
        for(int i=0;i<n-k;i++){
            slow = slow.next;
        }
        return slow;
    }
}