uva 12300 – Smallest Regular Polygon

題意：給定兩個點A和B，求包含這兩個點的面積最小的正 n（已知）邊形。

#include<iostream>#include<iomanip>#include<cmath>#define pi 2.0*asin(1.0)#define sqr(a) ((a)*(a))using namespace std;int main(){    int n;    double x1,x2,y1,y2,d,thy,s;    while(cin>>x1>>y1>>x2>>y2>>n && x1+x2+y1+y2+n)    {        d=sqrt(sqr(x1-x2)+sqr(y1-y2));        thy=pi-2*pi/n;        if(n%2)            s=n*sqr(d*cos((thy+pi)/4))*tan(thy/2);        else            s=n*sqr(d/2)*sin(thy)/2;        cout<<fixed<<setprecision(6)<<s<<endl;    }    return 0;}