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 3.1415926535897932
using 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;
}