题库练习 Neko Rules the Catniverse (Small Version)
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A12486 | Neko Rules the Catniverse (Small Version)

时间限制1s
内存限制256MB
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题目描述

This problem is same as the next one, but has smaller constraints.

Aki is playing a new video game. In the video game, he will control Neko, the giant cat, to fly between planets in the Catniverse.

There are $n$ planets in the Catniverse, numbered from $1$ to $n$ . At the beginning of the game, Aki chooses the planet where Neko is initially located. Then Aki performs $k - 1$ moves, where in each move Neko is moved from the current planet $x$ to some other planet $y$ such that:

- Planet $y$ is not visited yet.
- $1 \leq y \leq x + m$ (where $m$ is a fixed constant given in the input)

This way, Neko will visit exactly $k$ different planets. Two ways of visiting planets are called different if there is some index $i$ such that the $i$ -th planet visited in the first way is different from the $i$ -th planet visited in the second way.

What is the total number of ways to visit $k$ planets this way? Since the answer can be quite large, print it modulo $10^9 + 7$ .

输入格式

The only line contains three integers $n$ , $k$ and $m$ ( $1 \le n \le 10^5$ , $1 \le k \le \min(n, 12)$ , $1 \le m \le 4$ ) — the number of planets in the Catniverse, the number of planets Neko needs to visit and the said constant $m$ .

输出格式

Print exactly one integer — the number of different ways Neko can visit exactly $k$ planets. Since the answer can be quite large, print it modulo $10^9 + 7$ .

输入输出样例

输入 #1
3 3 1
输出 #1
4
输入 #2
4 2 1
输出 #2
9
输入 #3
5 5 4
输出 #3
120
输入 #4
100 1 2
输出 #4
100
C++ 编辑器
输入
输出