P15736 [JAG 2024 Summer Camp #2] Half Plane Painting
Description
You have a 2D plane that is initially entirely white. You can perform the following operation any number of times:
- Choose a line and the half-plane bounded by this line. Then, perform one of the following actions:
- Paint the half-plane (excluding the boundary) black.
- Paint the half-plane and the boundary white.
You are given the polygon $P$ with $N$ vertices, which is not necessarily convex. The vertices of $P$ are given in counterclockwise order as $(x_1, y_1)$, $(x_2, y_2)$, $\ldots$, $(x_N, y_N)$, and the $i$-th edge of $P$ connects vertex $(x_i, y_i)$ to vertex $(x_{(i \mod N) + 1}, y_{(i \mod N) + 1})$.
Determine whether it is possible to use the aforementioned operations to paint only the interior of polygon $P$ black, leaving everything else white.
Input Format
The input is given in the following format:
$$
\begin{aligned}
&N \\
&x_1 \ y_1 \\
&x_2 \ y_2 \\
&\vdots \\
&x_N \ y_N
\end{aligned}
$$
- $3 \leq N \leq 4,000$
- $-10^7 \leq x_i, y_i \leq 10^7 \quad (1 \leq i \leq N)$
- $(x_i, y_i) \neq (x_j, y_j) \quad (i \neq j)$
- The vertices of polygon $P$ are given in counterclockwise order.
- The edges of polygon $P$ do not share any points other than the vertices.
- Each internal angle of polygon $P$ is not $180$ degrees.
- All input values are integers.
Output Format
If it is possible to achieve the desired state with the operations, output **Yes**; otherwise, output **No**.