delete pics to save space

2.1077.cpp

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+#include<cstdio>
+#include<cmath>
+#include<algorithm>
+#include<cassert>
+using namespace std;
+struct Point
+{
+	double x,y;
+	Point(double _x=0,double _y=0):x(_x),y(_y) { }
+	inline bool operator<(const Point &b) { return x<b.x||(x==b.x&&y<b.y); }
+};
+typedef Point Vector;
+inline Vector operator+(const Vector &a,const Vector &b) { return Vector(a.x+b.x,a.y+b.y); }
+inline Vector operator-(const Vector &a,const Vector &b) { return Vector(a.x-b.x,a.y-b.y); }
+inline Vector operator*(const Vector &a,double b) { return Vector(a.x*b,a.y*b); }
+inline Vector operator/(const Vector &a,double b) { return Vector(a.x/b,a.y/b); }
+inline double Dot(const Vector &a,const Vector &b) { return a.x*b.x+a.y*b.y; }
+inline double Cross(const Vector &a,const Vector &b) { return a.x*b.y-a.y*b.x; }
+inline double Length(const Vector &a) { return sqrt(Dot(a,a)); }
+const double eps=1e-6;
+inline int dcmp(double x) { return fabs(x)<eps?0:(x>0?1:-1); }
+inline bool SIT(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 Point LIT(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;
+}
+
+const int maxn=105;
+int n,kase;
+double x[maxn*3+maxn*maxn];
+Point L[maxn][2][2];
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d",&n)==1&&n)
+	{
+		int c=0; double res=0;
+		for(int i=0;i<n;i++)
+		{
+			double X,H,B;
+			scanf("%lf%lf%lf",&X,&H,&B);
+			L[i][0][0]=Point(X-B*0.5,0);
+			L[i][0][1]=L[i][1][0]=Point(X,H);
+			L[i][1][1]=Point(X+B*0.5,0);
+			x[c++]=X-B*0.5; x[c++]=X; x[c++]=X+B*0.5;
+		}
+#ifdef debug
+		printf("Points:\n");
+		for(int i=0;i<n;i++)
+			printf("(%g,%g)\n(%g,%g)\n(%g,%g)\n"
+				,L[i][0][0].x,L[i][0][0].y
+				,L[i][0][1].x,L[i][0][1].y
+				,L[i][1][1].x,L[i][1][1].y);
+		printf("\n");
+#endif
+		for(int i=0;i<n;i++) for(int a=0;a<2;a++)
+			for(int j=i+1;j<n;j++) for(int b=0;b<2;b++)
+			{
+				Point &P1=L[i][a][0],&P2=L[i][a][1],&P3=L[j][b][0],&P4=L[j][b][1];
+				if(SIT(P1,P2,P3,P4))
+				{
+					x[c++]=LIT(P1,P2-P1,P3,P4-P3).x;
+					double nowx=x[c-1];
+					assert(P1.x<=P2.x);
+					assert(P3.x<=P4.x);
+					assert(P1.x<=nowx&&nowx<=P2.x);
+					assert(P3.x<=nowx&&nowx<=P4.x);
+				}
+			}
+		sort(x,x+c);
+		c=unique(x,x+c)-x;
+		Point l=Point(x[0],0);
+#ifdef debug
+		printf("x:\n");
+		for(int i=0;i<c;i++) printf("%.5lf\n",x[i]);
+		printf("\n");
+#endif
+		for(int i=1;i<c;i++)
+		{
+			Point r=Point(x[i],0);
+			double lx=x[i-1],rx=x[i];
+			for(int j=0;j<n;j++) for(int a=0;a<2;a++)
+			{
+				Point &P1=L[j][a][0],&P2=L[j][a][1];
+				assert(P1.x<=P2.x);
+				if(P1.x<=lx&&lx<=P2.x&&P1.x<=rx&&rx<=P2.x)
+				{
+					Vector v=P2-P1;
+					Point tr=P1+v*(rx-P1.x)/(P2.x-P1.x);
+					if(tr.y>=r.y) r=tr;
+				}
+			}
+			l.y=max(l.y,0.0);
+			if(dcmp(l.y)||dcmp(r.y))
+			{
+				res+=Length(r-l);
+#ifdef debug
+				printf("i=%d res+=%.5lf l=(%.5lf,%.5lf) r=(%.5lf,%.5lf)\n"
+					,i,Length(r-l)
+					,l.x,l.y
+					,r.x,r.y);
+				assert(dcmp(r.x-x[i])==0);
+				assert(dcmp(r.y+1));
+#endif
+			}
+#ifdef debug
+			printf("after i=%d res is %.5lf\n",i,res);
+			printf("\n");
+#endif
+			l=r;
+		}
+		printf("Case %d: %.0lf\n\n",++kase,res);
+	}
+	return 0;
+}
+/*
+1
+100 50 100
+3
+20  30  35
+37 24   29
+60 20 13
+0
+*/