109 lines
2.1 KiB
C++
109 lines
2.1 KiB
C++
#include<cstdio>
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#include<cstdlib>
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#include<cmath>
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#include<vector>
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#include<algorithm>
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using std::sort;
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struct Point
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{
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double x,y;
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Point(double x=0,double y=0):x(x),y(y){}
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};
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typedef Point Vector;
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inline Vector operator+(const Vector &A,const Vector &B)
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{ return Vector(A.x+B.x,A.y+B.y); }
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inline Vector operator-(const Point &a,const Point &b)
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{ return Vector(a.x-b.x,a.y-b.y); }
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inline Vector operator*(const Vector &A,double p)
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{ return Vector(A.x*p,A.y*p); }
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inline Vector operator/(const Vector &A,double p)
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{ return Vector(A.x/p,A.y/p); }
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inline bool operator<(const Point &a,const Point &b)
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{ return a.x<b.x||(a.x==b.x&&a.y<b.y); }
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const double ops=1e-10;
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inline int dcmp(double x)
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{ return (x>0?x:-x)<ops?0:(x>0?1:-1); }
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const double Pi=atan(1)*4;
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inline double D_to_R(double D)
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{ return Pi/180*D; }
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inline double Cross(const Vector &A,const Vector &B)
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{ return A.x*B.y-A.y*B.x; }
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inline Vector Rotate(const Vector &A,double rad)
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{
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double csr=cos(rad),sir=sin(rad);
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return Vector(A.x*csr-A.y*sir,A.x*sir+A.y*csr);
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}
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inline double PolygonArea(Point* p,int n)
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{
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double area=0;
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for(int i=1;i<n-1;i++)
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area+=Cross(p[i]-p[0],p[i+1]-p[0]);
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return area/2;
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}
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int ConvexHull(Point *p,int n,Point *ch)
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{
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sort(p,p+n);
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int m=0;
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for(int i=0;i<n;i++)
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{
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while(m>1&&Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
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ch[m++]=p[i];
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}
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int k=m;
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for(int i=n-2;i>=0;i--)
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{
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while(m>k&&Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
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ch[m++]=p[i];
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}
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if(n>1) m--;
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return m;
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}
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using namespace std;
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int T,n,m;
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double sumx,sumy,res;
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Point p[10005],ch[10005];
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double X1,Y1,X2,Y2;
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double A,B,C;
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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scanf("%d",&T);
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for(int kase=1;kase<=T;kase++)
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{
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scanf("%d",&n);
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sumx=0;sumy=0;
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for(int i=0;i<n;i++)
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{
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scanf("%lf%lf",&p[i].x,&p[i].y);
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sumx+=p[i].x;
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sumy+=p[i].y;
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}
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m=ConvexHull(p,n,ch);
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res=1e20;
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if(m<=2) res=0;
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else for(int i=0;i<m;i++)
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{
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X1=ch[i].x;Y1=ch[i].y;X2=ch[(i+1)%m].x;Y2=ch[(i+1)%m].y;
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A=Y2-Y1;
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B=X1-X2;
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C=X2*Y1-X1*Y2;
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res=min(res,fabs(A*sumx+B*sumy+C*n)/sqrt(A*A+B*B));
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}
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printf("Case #%d: %.3lf\n",kase,res/n);
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}
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return 0;
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}
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