154 lines
3.5 KiB
C++
154 lines
3.5 KiB
C++
#include<cstdio>
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#include<cstdlib>
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#include<cmath>
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#include<algorithm>
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using namespace std;
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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 Point read_point()
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{
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Point A;
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scanf("%lf%lf",&A.x,&A.y);
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return A;
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}
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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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inline bool operator==(const Point &a,const Point &b)
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{ return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0; }
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inline double Dot(const Vector &A,const Vector &B)
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{ return A.x*B.x+A.y*B.y; }
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inline double Length(const Vector &A)
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{ return sqrt(Dot(A,A)); }
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inline double Angle(const Vector &A,const Vector &B)
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{ return acos(Dot(A,B)/Length(A)/Length(B)); }
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const double Pi=atan(1)*4;
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inline double PAG(const Vector &A)
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{ return atan2(A.y,A.x); }
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inline double R_to_D(double rad)
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{ return 180/Pi*rad; }
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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 double Area2(const Point &a,const Point &b,const Point &c)
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{ return Cross(b-a,c-a); }
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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 Vector Normal(const Vector &A)
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{
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double L=Length(A);
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return Vector(-A.y/L,A.x/L);
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}
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inline Point GetLineIntersection
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(const Point &P,const Vector &v,const Point &Q,const Vector &w)
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{
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Vector u=P-Q;
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double t=Cross(w,u)/Cross(v,w);
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return P+v*t;
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}
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inline double DistanceToLine
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(const Point &P,const Point &A,const Point &B)
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{
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Vector v1=B-A,v2=P-A;
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return fabs(Cross(v1,v2))/Length(v1);
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}
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inline double DistanceToSegment
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(const Point &P,const Point &A,const Point &B)
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{
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if(A==B) return Length(P-A);
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Vector v1=B-A,v2=P-A,v3=P-B;
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if(dcmp(Dot(v1,v2))<0) return Length(v2);
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else if(dcmp(Dot(v1,v3))>0) return Length(v3);
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else return fabs(Cross(v1,v2))/Length(v1);
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}
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inline Point GetLineProjection
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(const Point &P,const Point &A,const Point &B)
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{
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Vector v=B-A;
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return A+v*(Dot(v,P-A)/Dot(v,v));
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}
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inline bool SegmentProperIntersection
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(const Point &a1,const Point &a2,const Point &b1,const Point &b2)
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{
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double c1=Cross(a2-a1,b1-a1),c2=Cross(a2-a1,b2-a1),
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c3=Cross(b2-b1,a1-b1),c4=Cross(b2-b1,a2-b1);
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return dcmp(c1)*dcmp(c2)<0&&dcmp(c3)*dcmp(c4)<0;
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}
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inline bool OnSegment
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(const Point &p,const Point &a1,const Point &a2)
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{ return dcmp(Cross(a1-p,a2-p))==0&&dcmp(Dot(a1-p,a2-p))<0; }
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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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const int maxn=310;
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Point P[maxn],V[maxn*maxn];
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int n,kase;
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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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while(scanf("%d",&n)==1&&n)
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{
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for(int i=0;i<n;i++) V[i]=P[i]=read_point();
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n--;
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int c=n,e=n;
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for(int i=0;i<n;i++)
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for(int j=i+1;j<n;j++)
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if(SegmentProperIntersection(P[i],P[i+1],P[j],P[j+1]))
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V[c++]=GetLineIntersection(P[i],P[i+1]-P[i],P[j],P[j+1]-P[j]);
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sort(V,V+c);
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c=unique(V,V+c)-V;
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for(int i=0;i<c;i++)
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for(int j=0;j<n;j++)
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if(OnSegment(V[i],P[j],P[j+1])) e++;
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printf("Case %d: There are %d pieces.\n",++kase,e+2-c);
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}
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return 0;
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}
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