好像写错了，应该是 $\dbinom{n-2}{d_1-1}=\cfrac{(n-2)!}{(d_1-1)!(n-d_1-1)!}$。
by 芷陌陌吖 @ 2023-12-01 10:45:11
@[feecle6418](/user/42156)
@[Maxmilite](/user/274993)
by 芷陌陌吖 @ 2023-12-01 10:46:17
@[Alex_wei](/user/123294)
by 芷陌陌吖 @ 2023-12-04 10:41:43
@[芷陌陌吖](/user/63444) Hack 数据已经添加，题解还请麻烦联系题解审核志愿者撤下。
by Maxmilite @ 2023-12-08 20:07:02
感谢
by 芷陌陌吖 @ 2023-12-08 21:00:17
@[_•́へ•́╬_](/user/90693) @[Acoipp](/user/674469)
by 芷陌陌吖 @ 2023-12-08 21:00:45
@[芷陌陌吖](/user/63444) 请提供毙掉的题解链接
by Acoipp @ 2023-12-08 21:04:50
@[Acoipp](/user/674469) 感谢，麻烦了
[1](https://www.luogu.com.cn/blog/Gary818/solution-p2290)
[2](https://www.luogu.com.cn/blog/stone41123/solution-p2290)
[3](https://www.luogu.com.cn/blog/user12066/solution-p2290)
by 芷陌陌吖 @ 2023-12-08 21:16:00
@[芷陌陌吖](/user/63444) deleted
by Acoipp @ 2023-12-08 21:49:33
太强了，过了这么久被HACK了
by Gary818 @ 2023-12-12 17:21:51