codeforces #306D Polygon 构造

题目大意：给定n，要求构造一个凸n边形，使得每个内角都相同，每条边长度都不同
膜拜题解
其实我一开始想的是构造一个正n边形然后把每条边微移一下……不过似乎不是很好写的样子= =

#include <cmath>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#define M 110#define PI 3.1415926535897932using namespace std;struct Point{    double x,y;    Point() {}    Point(double _,double __):        x(_),y(__) {}    friend Point operator + (const Point &p1,const Point &p2)    {        return Point(p1.x+p2.x,p1.y+p2.y);    }    friend Point operator - (const Point &p1,const Point &p2)    {        return Point(p1.x-p2.x,p1.y-p2.y);    }    friend double operator * (const Point &p1,const Point &p2)    {        return p1.x*p2.y-p1.y*p2.x;    }    friend Point operator * (const Point &p,double rate)    {        return Point(p.x*rate,p.y*rate);    }    friend Point Rotate (const Point &p,double alpha)    {        return Point(p.x*cos(alpha)-p.y*sin(alpha),p.x*sin(alpha)+p.y*cos(alpha) );    }}ans[M];struct Line{    Point p,v;    Line() {}    Line(const Point &_,const Point &__):        p(_),v(__) {}    friend Point Get_Intersection(const Line &l1,const Line &l2)    {        Point u=l1.p-l2.p;        double temp=(l2.v*u)/(l1.v*l2.v);        return l1.p+l1.v*temp;    }};int n;int main(){    int i;    cin>>n;    if(n<=4)        return cout<<"No solution"<<endl,0;    Point v(-1,0);    double len=450.0,delta=0.005;    double alpha=2.0*PI/n;    for(i=1;i<n;i++)    {        ans[i]=ans[i-1]+v*len;        len+=delta;        v=Rotate(v,-alpha);    }    ans[n]=Get_Intersection(Line(ans[n-1],v),Line(Point(0,0),Point(1,0)));    for(i=n;i;i--)        printf("%.10lf %.10lf\n",ans[i].x,ans[i].y);    return 0;}