Little Peter Ivanov likes to play knights. Or musketeers. Or samurai. It depends on his mood. For parents, it is still always looks like “he again found a stick and peels the trees.” They cannot understand that it is a sword. Or epee. Or katana.
Today Peter has found a shield. Actually, it is a board from the fence; fortunately, the nails from it have already been pulled. Peter knows that the family coat of arms should be depicted on the knight’s shield. The coat of arms of Ivanovs is a rectangle inscribed in a triangle (only grandfather supports Peter’s game, and he is, after all, a professor of mathematics). Peter has already drawn the triangle, and then noticed that there is a hole from a nail inside the triangle. It is not very good, so Peter wants to draw a rectangle in such a way that the hole will be on its border.
Because of the rectangle in Peter’s family symbolizes the authority and power then Peter wants to draw a rectangle of maximum area.
And due to the fact, that Peter is a grandson of grandfather-mathematician, he is also interested in purely theoretical question — how many different rectangles, satisfying the conditions, can be drawn in the triangle.
Help Peter to find the answers to these questions.

Input

The four lines contain the coordinates of four points that are the vertices of the triangle and the hole, respectively. All coordinates are integers and do not exceed 10 4 in absolute value. It is guaranteed that the hole is strictly inside the triangle. Also it is guaranteed that the triangle vertices do not lie on one line.

Output

In the first line output the maximum area of a rectangle, which Peter can draw. The answer will be considered correct if a relative or absolute error of maximum area does not exceed 10 −6.
In the second line output the number of different rectangles that Peter can draw (these rectangles are not required to have the maximum area).

Example

input output
0 0
10 0
0 20
4 6
48.0000000000
4
-3 0
2 -1
5 7
0 1
9.0697674419
2

Notes

The rectangle is called inscribed in a triangle if all its vertices lie on the sides of the triangle.

把三角形按锐角、直角、钝角分类讨论,看点p是否在三条高上。锐角三角形的答案在3-6之间,直角在3-4之间,钝角在1-2之间。

需要求点在直线上的射影,然后再相似三角形啦,正切函数啥的啦搞一下面积就出来了。

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
#define EPS 0.00000001
struct Point
{
double x,y;
Point(const double &X,const double &Y)
{
x=X;
y=Y;
}
Point(){}
double Length()
{
return sqrt(x*x+y*y);
}
}p,a[4];
typedef Point Vector;
double Dot(const Vector &a,const Vector &b)
{
return a.x*b.x+a.y*b.y;
}
Vector operator - (const Vector &a,const Vector &b)
{
return Vector(a.x-b.x,a.y-b.y);
}
Vector operator + (const Vector &a,const Vector &b)
{
return Vector(a.x+b.x,a.y+b.y);
}
double Cross(const Vector &a,const Vector &b)
{
return a.x*b.y-a.y*b.x;
}
double DisToLine(Point P,Point A,Point B)
{
Vector v1=B-A,v2=P-A;
return fabs(Cross(v1,v2))/v1.Length();
}
double tanget(Point a,Point b,Point c)//a是顶点
{
double COS=Dot(b-a,c-a)/(b-a).Length()/(c-a).Length();
double SIN=sqrt((1.0-COS*COS));
return SIN/COS;
}
Vector operator * (const double &x,const Vector &v)
{
return Vector(x*v.x,x*v.y);
}
Point GetLineProjection(Point P,Point A,Point B)
{
Vector v=B-A;
return A+(Dot(v,P-A)/Dot(v,v))*v;
}
double area;
int main()
{
//freopen("b.in","r",stdin);
for(int i=1;i<=3;++i)
scanf("%lf%lf",&a[i].x,&a[i].y);
scanf("%lf%lf",&p.x,&p.y);
int flag=0,ans=0;
//钝角三角形
if(Dot(a[2]-a[1],a[3]-a[1])<-EPS)
{
double dis=DisToLine(p,a[2],a[3]);
area=dis*((a[2]-a[3]).Length()-dis/tanget(a[2],a[1],a[3])-dis/tanget(a[3],a[1],a[2]));
if(fabs(Dot(a[1]-p,a[2]-a[3]))<EPS)
ans=1;
else
{
ans=2;
Point p1=GetLineProjection(a[1],a[2],a[3]);
Point p2=GetLineProjection(p,a[2],a[3]);
double h=(a[1]-p1).Length();
double h1;
if(Dot(p-p1,a[2]-p1)>EPS)
h1=(p2-a[2]).Length()/(p1-a[2]).Length()*h;
else
h1=(p2-a[3]).Length()/(p1-a[3]).Length()*h;
double l1=(h-h1)/h*(a[2]-a[3]).Length();
area=max(area,h1*l1);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
else if(Dot(a[1]-a[2],a[3]-a[2])<-EPS)
{
double dis=DisToLine(p,a[1],a[3]);
area=dis*((a[1]-a[3]).Length()-dis/tanget(a[1],a[2],a[3])-dis/tanget(a[3],a[1],a[2]));
if(fabs(Dot(a[2]-p,a[1]-a[3]))<EPS)
ans=1;
else
{
ans=2;
Point p1=GetLineProjection(a[2],a[1],a[3]);
Point p2=GetLineProjection(p,a[1],a[3]);
double h=(a[2]-p1).Length();
double h1;
if(Dot(p-p1,a[1]-p1)>EPS)
h1=(p2-a[1]).Length()/(p1-a[1]).Length()*h;
else
h1=(p2-a[3]).Length()/(p1-a[3]).Length()*h;
double l1=(h-h1)/h*(a[1]-a[3]).Length();
area=max(area,h1*l1);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
else if(Dot(a[1]-a[3],a[2]-a[3])<-EPS)
{
double dis=DisToLine(p,a[1],a[2]);
area=dis*((a[1]-a[2]).Length()-dis/tanget(a[1],a[2],a[3])-dis/tanget(a[2],a[1],a[3]));
if(fabs(Dot(a[3]-p,a[1]-a[2]))<EPS)
ans=1;
else
{
ans=2;
Point p1=GetLineProjection(a[3],a[1],a[2]);
Point p2=GetLineProjection(p,a[1],a[2]);
double h=(a[3]-p1).Length();
double h1;
if(Dot(p-p1,a[1]-p1)>EPS)
h1=(p2-a[1]).Length()/(p1-a[1]).Length()*h;
else
h1=(p2-a[2]).Length()/(p1-a[2]).Length()*h;
double l1=(h-h1)/h*(a[1]-a[2]).Length();
area=max(area,h1*l1);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
//直角三角形
if(fabs(Dot(a[2]-a[1],a[3]-a[1]))<EPS)
{
double dis=DisToLine(p,a[2],a[3]);
area=dis*((a[2]-a[3]).Length()-dis/tanget(a[2],a[1],a[3])-dis/tanget(a[3],a[1],a[2]));
if(fabs(Dot(a[1]-p,a[2]-a[3]))<EPS)
ans=3;
else
{
ans=4;
Point p1=GetLineProjection(a[1],a[2],a[3]);
Point p2=GetLineProjection(p,a[2],a[3]);
double h=(a[1]-p1).Length();
double h1;
if(Dot(p-p1,a[2]-p1)>EPS)
h1=(p2-a[2]).Length()/(p1-a[2]).Length()*h;
else
h1=(p2-a[3]).Length()/(p1-a[3]).Length()*h;
double l1=(h-h1)/h*(a[2]-a[3]).Length();
area=max(area,h1*l1); Point p3=GetLineProjection(p,a[1],a[3]);
double h2=(p3-a[3]).Length()/(a[1]-a[3]).Length()*(a[1]-a[2]).Length();
Point p4=GetLineProjection(p,a[1],a[2]);
double l2=(a[1]-a[3]).Length()-h2/tanget(a[3],a[1],a[2]);
area=max(area,h2*l2); double h3=(p4-a[2]).Length()/(a[1]-a[2]).Length()*(a[1]-a[3]).Length();
double l3=(a[1]-a[2]).Length()-h3/tanget(a[2],a[1],a[3]);
area=max(area,h3*l3);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
else if(fabs(Dot(a[1]-a[2],a[3]-a[2]))<EPS)
{
double dis=DisToLine(p,a[1],a[3]);
area=dis*((a[1]-a[3]).Length()-dis/tanget(a[1],a[2],a[3])-dis/tanget(a[3],a[1],a[2]));
if(fabs(Dot(a[2]-p,a[1]-a[3]))<EPS)
ans=3;
else
{
ans=4;
Point p1=GetLineProjection(a[2],a[1],a[3]);
Point p2=GetLineProjection(p,a[1],a[3]);
double h=(a[2]-p1).Length();
double h1;
if(Dot(p-p1,a[1]-p1)>EPS)
h1=(p2-a[1]).Length()/(p1-a[1]).Length()*h;
else
h1=(p2-a[3]).Length()/(p1-a[3]).Length()*h;
double l1=(h-h1)/h*(a[1]-a[3]).Length();
area=max(area,h1*l1); Point p3=GetLineProjection(p,a[2],a[3]);
double h2=(p3-a[3]).Length()/(a[2]-a[3]).Length()*(a[1]-a[2]).Length();
Point p4=GetLineProjection(p,a[1],a[2]);
double l2=(a[2]-a[3]).Length()-h2/tanget(a[3],a[1],a[2]);
area=max(area,h2*l2); double h3=(p4-a[1]).Length()/(a[1]-a[2]).Length()*(a[2]-a[3]).Length();
double l3=(a[1]-a[2]).Length()-h3/tanget(a[1],a[2],a[3]);
area=max(area,h3*l3);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
else if(fabs(Dot(a[1]-a[3],a[2]-a[3]))<EPS)
{
double dis=DisToLine(p,a[1],a[2]);
area=dis*((a[1]-a[2]).Length()-dis/tanget(a[1],a[2],a[3])-dis/tanget(a[2],a[1],a[3]));
if(fabs(Dot(a[3]-p,a[1]-a[2]))<EPS)
ans=3;
else
{
ans=4;
Point p1=GetLineProjection(a[3],a[1],a[2]);
Point p2=GetLineProjection(p,a[1],a[2]);
double h=(a[3]-p1).Length();
double h1;
if(Dot(p-p1,a[1]-p1)>EPS)
h1=(p2-a[1]).Length()/(p1-a[1]).Length()*h;
else
h1=(p2-a[2]).Length()/(p1-a[2]).Length()*h;
double l1=(h-h1)/h*(a[1]-a[2]).Length();
area=max(area,h1*l1); Point p3=GetLineProjection(p,a[2],a[3]);
double h2=(p3-a[2]).Length()/(a[2]-a[3]).Length()*(a[1]-a[3]).Length();
Point p4=GetLineProjection(p,a[1],a[3]);
double l2=(a[2]-a[3]).Length()-h2/tanget(a[2],a[1],a[3]);
area=max(area,h2*l2); double h3=(p4-a[1]).Length()/(a[1]-a[3]).Length()*(a[2]-a[3]).Length();
double l3=(a[1]-a[3]).Length()-h3/tanget(a[1],a[2],a[3]);
area=max(area,h3*l3);
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}
//锐角三角形
for(int i=1;i<=3;++i)//枚举上顶点
{
int j,k;
if(i==1) j=2,k=3;
else if(i==2) j=3,k=1;
else j=1,k=2;
double dis=DisToLine(p,a[j],a[k]);
area=max(area,dis*((a[j]-a[k]).Length()-dis/tanget(a[j],a[i],a[k])-dis/tanget(a[k],a[i],a[j])));
if(fabs(Dot(a[i]-p,a[k]-a[j]))<EPS)
++ans;
else
{
ans+=2;
Point p1=GetLineProjection(a[i],a[j],a[k]);
Point p2=GetLineProjection(p,a[j],a[k]);
double h=(a[i]-p1).Length();
double h1;
if(Dot(p-p1,a[j]-p1)>EPS)
h1=(p2-a[j]).Length()/(p1-a[j]).Length()*h;
else
h1=(p2-a[k]).Length()/(p1-a[k]).Length()*h;
double l1=(h-h1)/h*(a[j]-a[k]).Length();
area=max(area,h1*l1);
}
}
printf("%.10lf\n%d\n",area,ans);
return 0;
}

【计算几何】URAL - 2101 - Knight's Shield的更多相关文章

  1. Ural 1298 Knight 题解

    目录 Ural 1298 Knight 题解 题意 题解 程序 Ural 1298 Knight 题解 题意 给定一个\(n\times n(1\le n\le8)\)的国际象棋棋盘和一个骑士(基本上 ...

  2. 转载:hdu 题目分类 (侵删)

    转载:from http://blog.csdn.net/qq_28236309/article/details/47818349 基础题:1000.1001.1004.1005.1008.1012. ...

  3. 杭电ACM分类

    杭电ACM分类: 1001 整数求和 水题1002 C语言实验题——两个数比较 水题1003 1.2.3.4.5... 简单题1004 渊子赛马 排序+贪心的方法归并1005 Hero In Maze ...

  4. Ural 1197 - Lonesome Knight

    The statement of this problem is very simple: you are to determine how many squares of the chessboar ...

  5. Ural 2036. Intersect Until You're Sick of It 计算几何

    2036. Intersect Until You're Sick of It 题目连接: http://acm.timus.ru/problem.aspx?space=1&num=2036 ...

  6. URAL 1775 B - Space Bowling 计算几何

    B - Space BowlingTime Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hust.edu.cn/vjudge/contest/ ...

  7. Ural 1046 Geometrical Dreams(解方程+计算几何)

    题目链接:http://acm.timus.ru/problem.aspx?space=1&num=1046 参考博客:http://hi.baidu.com/cloudygoose/item ...

  8. URAL 2099 Space Invader题解 (计算几何)

    啥也不说了,直接看图吧…… 代码如下: #include<stdio.h> #include<iostream> #include<math.h> using na ...

  9. URAL 1966 Cycling Roads 计算几何

    Cycling Roads 题目连接: http://acm.hust.edu.cn/vjudge/contest/123332#problem/F Description When Vova was ...

随机推荐

  1. 一个简易的Python全站抓取系统

    很长时间没有更新博客了,前一阵时间在做项目,里面有一个爬虫系统,然后就从里面整理了一点代码做成了一个简易的爬虫系统,还挺实用的. 简单说来,这个爬虫系统的功能就是:给定初始的链接池,然后设定一些参数, ...

  2. bzoj 1201[HNOI2005]数三角形 1202 [HNOI2005]狡猾的商人 暴力 权值并查集

    [HNOI2005]数三角形 Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 349  Solved: 234[Submit][Status][Disc ...

  3. javaScript中的this关键字解析

    this是JavaScript中的关键字之一,在编写程序的时候经常会用到,正确的理解和使用关键字this尤为重要.接下来,笔者就从作用域的角度粗谈下自己对this关键字的理解,希望能给到大家一些启示, ...

  4. 关于MyBatis的collection集合中只能取到一条数据的问题

    问题:在涉及多表查询的时候,使用collection元素来映射集合属性时,出现了只能查询到一条数据的情况,但用sql语句在数据库中查询会有多条记录. 解决:如果两表联查,主表和明细表的主键都是id的话 ...

  5. Http/2 升级指南

    [转]http://www.syyong.com/architecture/http2.html HTTP/2(最初名为HTTP/2.0)是 WWW 使用的 HTTP 网络协议的主要版本. 它来自早先 ...

  6. Eclipse Tomcat部署项目没有加载新加的静态资源文件

    额,一直用MyEclipse,后来用Eclipse时,启动项目后去Tomcat webapps找对应文件夹,发现没有,才知道Eclipse 默认不往本地Tomcat部署. 1.eclipse不像MyE ...

  7. ecma 2018, javascript spread syntax behaves like Object.assign

    as the subject. It is only supported in Chrome version 60+, so, first check the version, or just use ...

  8. Python爬虫学习 - day1 - 爬取图片

    利用Python完成简单的图片爬取 最近学习到了爬虫,瞬时觉得很高大上,想取什么就取什么,感觉要上天.这里分享一个简单的爬取汽车之家文章列表的图片教程,供大家学习. 需要的知识点储备 本次爬虫脚本依赖 ...

  9. python基础===python3 get和post请求(转载)

    get请求 #encoding:UTF-8 importurllib importurllib.request data={} data['name']='aaa' url_parame=urllib ...

  10. 【POI2017||bzoj4726】Sabota?

    上学期putsnan过了一次,这学期认真写了一遍…… #include<bits/stdc++.h> #define N 500010 using namespace std; ]; ,n ...