ZOJ 1696 Viva Confetti 计算几何 - c++编程基础

计算几何：按顺序给n个圆覆盖，问最后可以有几个圆被看见。。。

对每个圆求和其他圆的交点，每两个交点之间就是可能被看到的圆弧，取圆弧的中点，往外扩展一点或者往里缩一点，从上往下判断有没有圆可以盖住这个点，能盖住这个点的最上面的圆一定是可见的

Viva Confetti

Time Limit: 2 Seconds Memory Limit: 65536 KB

Do you know confetti? They are small discs of colored paper, and people throw them around during parties or festivals. Since people throw lots of confetti, they may end up stacked one on another, so there may be hidden ones underneath.

A handful of various sized confetti have been dropped on a table. Given their positions and sizes, can you tell us how many of them you can see?

The following figure represents the disc configuration for the first sample input, where the bottom disc is still visible.

Input

The input is composed of a number of configurations of the following fZ??http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">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"brush:java;">#include #include #include #include #include using namespace std; const double eps=5*(1e-13); const double pi=acos(-1.0); int n; struct Point { double x,y; Point(){} Point(double _x,double _y):x(_x),y(_y){} }; struct Ci

ZOJ 1696 Viva Confetti 计算几何(一)