Difference between revisions of "2019 Multi-University,HDU Day 9"
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| Line 6: | Line 6: | ||
g_m(i)=\left\{ | g_m(i)=\left\{ | ||
\begin{aligned} | \begin{aligned} | ||
| − | 0(1 \le i \le m) \\ | + | &0&(1 \le i \le m) \\ |
| − | i-1+\frac{1}{i}\sum_{j=1}^i(g_m(j-1)+g_m(i-j)) | + | &i-1+\frac{1}{i}\sum_{j=1}^i(g_m(j-1)+g_m(i-j))&(m<i) |
\end{aligned} | \end{aligned} | ||
\right. | \right. | ||
Revision as of 14:05, 19 August 2019
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}
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.