题解 | #链表中倒数最后k个结点#

注意首先判断参数为空的情况

/*
 * 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(k == 0 || pHead == null){
            return null;
        }
        ListNode pre = pHead;
        ListNode cur = pHead;
        
        for(int i = 0;i<k-1;i++){
            if(cur.next == null){
                return null;
            }
            cur = cur.next;
            
        }
        
        while(cur.next!=null){
            cur = cur.next;
            pre = pre.next;
        }
        return pre;
    }
}