题解 | #删除链表的倒数第n个节点#

/*
 * 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
        if (head == null || n < 1) {
            return head;
        }
        int len = 0;
        ListNode cur = head;
        while (cur != null) {
            len++;
            cur = cur.next;
        }
        
        if (len < n) {
            return head;
        } else if (len == n) {
            return head.next;
        }
        
        ListNode pre = head;
        cur = pre;
        int i = 0;
        ListNode next = null;
        while (i < len - n) {
            next = cur.next;
            pre = cur;
            cur = next;
            i++;
        }
        
        pre.next = cur.next;
        cur.next = null;
        return head;
    }
    
    
    
    
    
}