NC53 删除链表的倒数第n个节点

增加一个头结点 方便统一操作。

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) {
        ListNode xxhead = new ListNode(0);
        xxhead.next = head;
        ListNode cur = head;
        int len = 0;
        int count = 1;
        while(cur != null){
            cur = cur.next;
            len ++;
        }
        ListNode prev = xxhead;
        cur = head;
        while(len-n+1 != count){
            ListNode temp = cur;
            cur = cur.next;
            prev = temp;
            count ++;
        }
        prev.next = cur.next;
        return xxhead.next;

    }
}