QOJ.ac

QOJ

Límite de tiempo: 2.0 s Límite de memoria: 256 MB Puntuación total: 100

#11936. 硬币

Estadísticas

Alice 和 Bob 正在玩一个简单的游戏。他们排成一排 $n$ 枚相同的硬币,所有硬币初始时正面朝下,背面朝上。

他们总共进行 $m$ 次操作,每次操作选择任意 $k$ 枚硬币并将它们抛向空中,每枚硬币以相同的概率变为正面朝上或背面朝上。他们的目标是使最终正面朝上的硬币数量尽可能多。

输入格式

输入包含多组测试数据,第一行包含一个整数 $t$ ($1 \le t \le 1000$),表示测试数据的总数。

对于每组测试数据,一行包含三个空格分隔的整数 $n, m$ ($1 \le n, m \le 100$) 和 $k$ ($1 \le k \le n$)。

输出格式

对于每组测试数据,输出在最优策略下,最终正面朝上的硬币数量的期望值,保留 3 位小数。

样例

样例输入 1

6
2 1 1
2 3 1
5 4 3
6 2 3
6 100 1
6 100 2

样例输出 1

0.500
1.250
3.479
3.000
5.500
5.000

Discussions

About Discussions

The discussion section is only for posting: General Discussions (problem-solving strategies, alternative approaches), and Off-topic conversations.

This is NOT for reporting issues! If you want to report bugs or errors, please use the Issues section below.

Open Discussions 0
No discussions in this category.

Issues

About Issues

If you find any issues with the problem (statement, scoring, time/memory limits, test cases, etc.), you may submit an issue here. A problem moderator will review your issue.

Guidelines:

  1. This is not a place to publish discussions, editorials, or requests to debug your code. Issues are only visible to you and problem moderators.
  2. Do not submit duplicated issues.
  3. Issues must be filed in English or Chinese only.
Active Issues 0
No issues in this category.
Closed/Resolved Issues 0
No issues in this category.