delete pics to save space

2.1342.cpp

@@ -0,0 +1,153 @@
+#include<cstdio>
+#include<cstdlib>
+#include<cmath>
+#include<algorithm>
+using namespace std;
+struct Point
+{
+	double x,y;
+	Point(double x=0,double y=0):x(x),y(y){}
+};
+typedef Point Vector;
+
+inline Point read_point()
+{
+	Point A;
+	scanf("%lf%lf",&A.x,&A.y);
+	return A;
+}
+
+inline Vector operator+(const Vector &A,const Vector &B)
+{ return Vector(A.x+B.x,A.y+B.y); }
+
+inline Vector operator-(const Point &a,const Point &b)
+{ return Vector(a.x-b.x,a.y-b.y); }
+
+inline Vector operator*(const Vector &A,double p)
+{ return Vector(A.x*p,A.y*p); }
+
+inline Vector operator/(const Vector &A,double p)
+{ return Vector(A.x/p,A.y/p); }
+
+inline bool operator<(const Point &a,const Point &b)
+{ return a.x<b.x||(a.x==b.x&&a.y<b.y); }
+
+const double ops=1e-10;
+inline int dcmp(double x)
+{ return (x>0?x:-x)<ops?0:(x>0?1:-1); }
+
+inline bool operator==(const Point &a,const Point &b)
+{ return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0; }
+
+inline double Dot(const Vector &A,const Vector &B)
+{ return A.x*B.x+A.y*B.y; }
+
+inline double Length(const Vector &A)
+{ return sqrt(Dot(A,A)); }
+
+inline double Angle(const Vector &A,const Vector &B)
+{ return acos(Dot(A,B)/Length(A)/Length(B)); }
+
+const double Pi=atan(1)*4;
+inline double PAG(const Vector &A)
+{ return atan2(A.y,A.x); }
+inline double R_to_D(double rad)
+{ return 180/Pi*rad; }
+inline double D_to_R(double D)
+{ return Pi/180*D; }
+
+inline double Cross(const Vector &A,const Vector &B)
+{ return A.x*B.y-A.y*B.x; }
+
+inline double Area2(const Point &a,const Point &b,const Point &c)
+{ return Cross(b-a,c-a); }
+
+inline Vector Rotate(const Vector &A,double rad)
+{
+	double csr=cos(rad),sir=sin(rad);
+	return Vector(A.x*csr-A.y*sir,A.x*sir+A.y*csr);
+}
+
+inline Vector Normal(const Vector &A)
+{
+	double L=Length(A);
+	return Vector(-A.y/L,A.x/L);
+}
+
+inline Point GetLineIntersection
+(const Point &P,const Vector &v,const Point &Q,const Vector &w)
+{
+	Vector u=P-Q;
+	double t=Cross(w,u)/Cross(v,w);
+	return P+v*t;
+}
+
+inline double DistanceToLine
+(const Point &P,const Point &A,const Point &B)
+{
+	Vector v1=B-A,v2=P-A;
+	return fabs(Cross(v1,v2))/Length(v1);
+}
+
+inline double DistanceToSegment
+(const Point &P,const Point &A,const Point &B)
+{
+	if(A==B) return Length(P-A);
+	Vector v1=B-A,v2=P-A,v3=P-B;
+	if(dcmp(Dot(v1,v2))<0) return Length(v2);
+	else if(dcmp(Dot(v1,v3))>0) return Length(v3);
+	else return fabs(Cross(v1,v2))/Length(v1);
+}
+
+inline Point GetLineProjection
+(const Point &P,const Point &A,const Point &B)
+{
+	Vector v=B-A;
+	return A+v*(Dot(v,P-A)/Dot(v,v));
+}
+
+inline bool SegmentProperIntersection
+(const Point &a1,const Point &a2,const Point &b1,const Point &b2)
+{
+	double c1=Cross(a2-a1,b1-a1),c2=Cross(a2-a1,b2-a1),
+		   c3=Cross(b2-b1,a1-b1),c4=Cross(b2-b1,a2-b1);
+	return dcmp(c1)*dcmp(c2)<0&&dcmp(c3)*dcmp(c4)<0;
+}
+
+inline bool OnSegment
+(const Point &p,const Point &a1,const Point &a2)
+{ return dcmp(Cross(a1-p,a2-p))==0&&dcmp(Dot(a1-p,a2-p))<0; }
+
+inline double PolygonArea(Point* p,int n)
+{
+	double area=0;
+	for(int i=1;i<n-1;i++)
+		area+=Cross(p[i]-p[0],p[i+1]-p[0]);
+	return area/2;
+}
+const int maxn=310;
+Point P[maxn],V[maxn*maxn];
+int n,kase;
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d",&n)==1&&n)
+	{
+		for(int i=0;i<n;i++) V[i]=P[i]=read_point();
+		n--;
+		int c=n,e=n;
+		for(int i=0;i<n;i++)
+			for(int j=i+1;j<n;j++)
+				if(SegmentProperIntersection(P[i],P[i+1],P[j],P[j+1]))
+					V[c++]=GetLineIntersection(P[i],P[i+1]-P[i],P[j],P[j+1]-P[j]);
+		sort(V,V+c);
+		c=unique(V,V+c)-V;
+		for(int i=0;i<c;i++)
+			for(int j=0;j<n;j++)
+				if(OnSegment(V[i],P[j],P[j+1])) e++;
+		printf("Case %d: There are %d pieces.\n",++kase,e+2-c);
+	}
+	return 0;
+}