delete pics to save space

5.1030B.cpp

@@ -0,0 +1,41 @@
+#include<cstdio>
+struct Point
+{
+	double x,y;
+	Point(double _x=0,double _y=0):x(_x),y(_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 double Cross(const Vector &a,const Vector &b) { return a.x*b.y-a.y*b.x; }
+int n,d,m,x,y;
+inline bool OnLeft(const Point &O,const Vector &v,const Point &P) { return Cross(v,P-O)>=0; }
+Point a1,a2,a3,a4;
+Vector v1,v2,v3,v4;
+inline bool in(int x,int y)
+{
+	Point p(x,y);
+	return OnLeft(a1,v1,p)&&OnLeft(a2,v2,p)&&OnLeft(a3,v3,p)&&OnLeft(a4,v4,p);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d%d%d",&n,&d,&m);
+	a1=Point(d,0);
+	a2=Point(n,n-d);
+	a3=Point(n-d,n);
+	a4=Point(0,d);
+	v1=a2-a1;
+	v2=a3-a2;
+	v3=a4-a3;
+	v4=a1-a4;
+	for(int i=0;i<m;i++)
+	{
+		scanf("%d%d",&x,&y);
+		if(in(x,y)) printf("YES\n");
+		else printf("NO\n");
+	}
+	return 0;
+}