@各位童鞋 不是求水题吗？
by Dream_Country @ 2024-03-21 21:08:38
@[Dream_Country](/user/1119053) [**1**](https://www.luogu.com.cn/problem/AT_abc048_b)
[**2**](https://www.luogu.com.cn/problem/AT_abc037_c)
[**3**](https://www.luogu.com.cn/problem/AT_abc148_e)
[**4**](https://www.luogu.com.cn/problem/P1112)
[**5**](https://www.luogu.com.cn/problem/P2181)**（公式：n*(n-1)/2*(n-2)/3*(n-3)/4）**
by define_sb_114514 @ 2024-03-21 21:21:51
@[define_sb_114514](/user/790516) 哇啊啊，极品好题！
by Dream_Country @ 2024-03-21 21:24:30
[还有这个](https://www.luogu.com.cn/problem/P3912)
by define_sb_114514 @ 2024-03-21 21:25:12
[P2386](https://www.luogu.com.cn/problem/P2386)
[P2440](https://www.luogu.com.cn/problem/P2440)
by define_sb_114514 @ 2024-03-21 21:30:22