题解 | #删除链表的倒数第n个节点#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param head ListNode类 
     * @param n int整型 
     * @return ListNode类
     */
    public ListNode removeNthFromEnd (ListNode head, int n) {
        // write code here
        ListNode preHead = new ListNode(0);
        preHead.next = head;
        ListNode p = head;
        int cnt = 0;
        while(p != null) {
            p = p.next;
            cnt++;
        }
        p = preHead;
        for(int i = 0;i < cnt - n;i++) {
            p = p.next;
        }
        p.next = p.next.next;
        return preHead.next;
    }
}