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 || k<=0 ) return null;
        ListNode slow = pHead;
        ListNode fast = pHead;
        while(k!=0){
            if(fast!=null){
            fast = fast.next;
            k--;
            }
            else
            return null;
        }
        while(fast!=null){
            slow = slow.next;
            fast = fast.next;       
        }
        return slow;
    }
}