LeetCode19. 删除链表的倒数第 N 个结点

class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        int length = 0;
        ListNode cur = head;
        while(cur != null) {
            length ++;     //计算链表长度
            cur = cur.next;
        }
        if(length == n) {
            return head.next;
        }
        ListNode temp = new ListNode();
        temp.next = head; //创建temp对象，让head的前一个节点为temp
        for(int i = 0; i < length; i++) {
            if(i == length - n) {
                temp.next = temp.next.next;
            }
            temp = temp.next;
        }
        return head;
    }
}