A9529 | The Child and Polygon
时间限制1s
内存限制256MB
通过 / 提交0/0
题目描述
This time our child has a simple polygon. He has to find the number of ways to split the polygon into non-degenerate triangles, each way must satisfy the following requirements:
- each vertex of each triangle is one of the polygon vertex;
- each side of the polygon must be the side of exactly one triangle;
- the area of intersection of every two triangles equals to zero, and the sum of all areas of triangles equals to the area of the polygon;
- each triangle must be completely inside the polygon;
- each side of each triangle must contain exactly two vertices of the polygon.
The picture below depicts an example of a correct splitting.
Please, help the child. Calculate the described number of ways modulo $1000000007$ $(10^{9}+7)$ for him.
- each vertex of each triangle is one of the polygon vertex;
- each side of the polygon must be the side of exactly one triangle;
- the area of intersection of every two triangles equals to zero, and the sum of all areas of triangles equals to the area of the polygon;
- each triangle must be completely inside the polygon;
- each side of each triangle must contain exactly two vertices of the polygon.
The picture below depicts an example of a correct splitting.
Please, help the child. Calculate the described number of ways modulo $1000000007$ $(10^{9}+7)$ for him.
输入格式
The first line contains one integer $n$ $(3<=n<=200)$ — the number of vertices of the polygon. Then follow $n$ lines, each line containing two integers. The $i$ -th line contains $x_{i},y_{i}$ $(|x_{i}|,|y_{i}|<=10^{7})$ — the $i$ -th vertex of the polygon in clockwise or counterclockwise order.
It's guaranteed that the polygon is simple.
It's guaranteed that the polygon is simple.
输出格式
Output the number of ways modulo $1000000007$ $(10^{9}+7)$ .
输入输出样例
输入 #1
4 0 0 0 1 1 1 1 0
输出 #1
2
输入 #2
4 0 0 1 0 0 1 -1 0
输出 #2
1
输入 #3
5 0 0 1 0 1 1 0 1 -2 -1
输出 #3
3
In the first sample, there are two possible splittings:
In the second sample, there are only one possible splitting:

In the second sample, there are only one possible splitting:

C++ 编辑器
输入
输出
可保存默认模板;新题优先使用已保存模板。
当前快捷键仅展示,暂不支持修改。
- 撤销
Ctrl / ⌘ + Z - 重做
Ctrl / ⌘ + Y - 查找
Ctrl / ⌘ + F - 全选
Ctrl / ⌘ + A - 复制
Ctrl / ⌘ + C - 剪切
Ctrl / ⌘ + X - 粘贴
Ctrl / ⌘ + V - 自动排版
工具栏排版按钮 - 草稿保存
编辑时自动保存到本机
历史
提交记录
状态说明时间源码
AI
作答助手
你好,我是作答助手。可以问思路、复杂度、样例含义或代码报错原因;不会直接给出完整 AC 代码。
确定要清空代码吗?
提交通过
评测结果:Accepted