0%

## 计算几何基础

### 单位向量 $(Unit\ vector)$

​ 对于任意向量 $\vec a$ ，不论方向如何，若其大小为单位长度，则称其为 $\vec a$ 方向上的单位向量 $(Unit\ vector)$ 。单位向量通常被记为 $\vec u$ 。

UVA - 11235

# Area

For a given polygon g, computes the area of the polygon.

g is represented by a sequence of points $p_1$, $p_2$,…, $p_n$ where line segments connecting pi and pi+1 (1 ≤ in−1) are sides of g. The line segment connecting pn and p1 is also a side of the polygon.

Note that the polygon is not necessarily convex.

# Distance

For given two segments s1 and s2, print the distance between them.

s1 is formed by end points p0 and p1, and s2 is formed by end points p2 and p3.