欧拉计划 发表于 2017-1-5 16:37:26

题目228:明可夫斯基和

Minkowski Sums

Let Sn be the regular n-sided polygon – or shape – whose vertices vk (k = 1,2,…,n) have coordinates:

        xk   =   cos( 2k-1/n ×180° )
        yk   =   sin( 2k-1/n ×180° )

Each Sn is to be interpreted as a filled shape consisting of all points on the perimeter and in the interior.

The Minkowski sum, S+T, of two shapes S and T is the result of adding every point in S to every point in T, where point addition is performed coordinate-wise: (u, v) + (x, y) = (u+x, v+y).

For example, the sum of S3 and S4 is the six-sided shape shown in pink below:



How many sides does S1864 + S1865 + … + S1909 have?

题目:

设 Sn 为正 n 多边形——或者说为顶点 vk (k = 1,2,…,n) 满足以下坐标的图形:

        xk =   cos( 2k-1/n ×180°)

        yk =   sin(2k-1/n ×180°)

每个 Sn 表示一个由边界上和图形内部的点组成的填充图形。

明可夫斯基和 S+T,为 T 中每个点加上 S 中每个点的结果,其中点的加法用坐标表示为:(u, v) + (x, y) = (u+x, v+y)。

例如,S3 与 S4 的和为下面的粉红色六边形:



S1864 + S1865 + … + S1909 有多少条边?


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