2019 Multi-University,HDU Day 9

Problem A

Solved by Kilo_5723. 02:16:39 (+)

题意：\begin{equation} g_m(i)=\left\{ \begin{aligned} &0&(1 \le i \le m) \\ &i-1+\frac{1}{i}\sum_{j=1}^i(g_m(j-1)+g_m(i-j))&(m<i) \end{aligned} \right. \end{equation} 求 $g_m(n)$。

Problem B

Solved by Xiejiadong && Kilo_5723. 03:38:23 (+)

题意：给出一些从边界出发的直线，求平面被分割成了几块。

题解：可以对交点分类讨论，因为保证了出发点不会同行也不会同列，所以只有两种交点是有贡献的：

• + 交点，且贡献为 $1$ ；

• 」 交点，贡献为 $0.5$ ，且只出现在边界上，共 $4$ 个，贡献为 $1$ 。

所以统计 + 交点个数，+1 就好了，需要区间加，单点询问，直接上树状数组。

Problem C

Upsolved by Kilo_5723 && Xiejiadong. (-5)

Problem D

Solved by Weaver_zhu. 00:15:48 (+)

Problem E

Solved by Kilo_5723. 04:07:47 (+9)

Problem F

Unsolved.

Problem G

Unsolved.

Problem H

Unsolved.

Problem I

Unsolved.

Problem J

Unsolved.

Problem K

Unsolved.