uva 12304 - 2D Geometry 110 in 1!（几何）

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题目链接：uva 12304 - 2D Geometry 110 in 1!

没什么好说的，根据操作直接处理。

#include <cstdio>
#include <cstring>
#include <cmath>
#include <vector>
#include <algorithm>

using namespace std;
const double pi = 4 * atan(1);
const double eps = 1e-9;

inline int dcmp (double x) { if (fabs(x) < eps) return 0; else return x < 0 ? -1 : 1; }
inline double getDistance (double x, double y) { return sqrt(x * x + y * y); }

struct Point {
	double x, y;
	Point (double x = 0, double y = 0): x(x), y(y) {}
	void read () { scanf("%lf%lf", &x, &y); }
	void write () { printf("%lf %lf", x, y); }

	bool operator == (const Point& u) const { return dcmp(x - u.x) == 0 && dcmp(y - u.y) == 0; }
	bool operator != (const Point& u) const { return !(*this == u); }
	bool operator < (const Point& u) const { return x < u.x || (x == u.x && y < u.y); }
	bool operator > (const Point& u) const { return u < *this; }
	bool operator <= (const Point& u) const { return *this < u || *this == u; }
	bool operator >= (const Point& u) const { return *this > u || *this == u; }
	Point operator + (const Point& u) { return Point(x + u.x, y + u.y); }
	Point operator - (const Point& u) { return Point(x - u.x, y - u.y); }
	Point operator * (const double u) { return Point(x * u, y * u); }
	Point operator / (const double u) { return Point(x / u, y / u); }
};

typedef Point Vector;

struct Line {
	double a, b, c;
	Line (double a = 0, double b = 0, double c = 0): a(a), b(b), c(c) {}
};

struct Circle {
	Point o;
	double r;
	Circle (Point o, double r = 0): o(o), r(r) {}
	Point point(double rad) { return Point(o.x + cos(rad)*r, o.y + sin(rad)*r); }
};


namespace Punctual {
	double getDistance (Point a, Point b) { double x=a.x-b.x, y=a.y-b.y; return sqrt(x*x + y*y); }
};

namespace Vectorial {
	/* 点积: 两向量长度的乘积再乘上它们夹角的余弦, 夹角大于90度时点积为负 */
	double getDot (Vector a, Vector b) { return a.x * b.x + a.y * b.y; }

	/* 叉积: 叉积等于两向量组成的三角形有向面积的两倍, cross(v, w) = -cross(w, v) */
	double getCross (Vector a, Vector b) { return a.x * b.y - a.y * b.x; }

	double getLength (Vector a) { return sqrt(getDot(a, a)); }
	double getAngle (Vector u) { return atan2(u.y, u.x); }
	double getAngle (Vector a, Vector b) { return acos(getDot(a, b) / getLength(a) / getLength(b)); }
	Vector rotate (Vector a, double rad) { return Vector(a.x*cos(rad)-a.y*sin(rad), a.x*sin(rad)+a.y*cos(rad)); }
	/* 单位法线 */
	Vector getNormal (Vector a) { double l = getLength(a); return Vector(-a.y/l, a.x/l); }
};

namespace Linear {
	using namespace Vectorial;

	Line getLine (double x1, double y1, double x2, double y2) { return Line(y2-y1, x1-x2, y1*(x2-x1)-x1*(y2-y1)); }
	Line getLine (double a, double b, Point u) { return Line(a, -b, u.y * b - u.x * a); }

	bool getIntersection (Line p, Line q, Point& o) {
		if (fabs(p.a * q.b - q.a * p.b) < eps)
			return false;
		o.x = (q.c * p.b - p.c * q.b) / (p.a * q.b - q.a * p.b);
		o.y = (q.c * p.a - p.c * q.a) / (p.b * q.a - q.b * p.a);
		return true;
	}

	/* 直线pv和直线qw的交点 */
	bool getIntersection (Point p, Vector v, Point q, Vector w, Point& o) {
		if (dcmp(getCross(v, w)) == 0) return false;
		Vector u = p - q;
		double k = getCross(w, u) / getCross(v, w);
		o = p + v * k;
		return true;
	}

	/* 点p到直线ab的距离 */
	double getDistanceToLine (Point p, Point a, Point b) { return fabs(getCross(b-a, p-a) / getLength(b-a)); }
	double getDistanceToSegment (Point p, Point a, Point b) {
		if (a == b) return getLength(p-a);
		Vector v1 = b - a, v2 = p - a, v3 = p - b;
		if (dcmp(getDot(v1, v2)) < 0) return getLength(v2);
		else if (dcmp(getDot(v1, v3)) > 0) return getLength(v3);
		else return fabs(getCross(v1, v2) / getLength(v1));
	}

	/* 点p在直线ab上的投影 */
	Point getPointToLine (Point p, Point a, Point b) { Vector v = b-a; return a+v*(getDot(v, p-a) / getDot(v,v)); }

	/* 判断线段是否存在交点 */
	bool haveIntersection (Point a1, Point a2, Point b1, Point b2) {
		double c1=getCross(a2-a1, b1-a1), c2=getCross(a2-a1, b2-a1), c3=getCross(b2-b1, a1-b1), c4=getCross(b2-b1,a2-b1);
		return dcmp(c1)*dcmp(c2) < 0 && dcmp(c3)*dcmp(c4) < 0;
	}

	/* 判断点是否在线段上 */
	bool onSegment (Point p, Point a, Point b) { return dcmp(getCross(a-p, b-p)) == 0 && dcmp(getDot(a-p, b-p)) < 0; }
}

namespace Triangular {
	using namespace Vectorial;

	double getAngle (double a, double b, double c) { return acos((a*a+b*b-c*c) / (2*a*b)); }
	double getArea (double a, double b, double c) { double s =(a+b+c)/2; return sqrt(s*(s-a)*(s-b)*(s-c)); }
	double getArea (double a, double h) { return a * h / 2; }
	double getArea (Point a, Point b, Point c) { return fabs(getCross(b - a, c - a)) / 2; }
};

namespace Polygonal {
	using namespace Vectorial;
	double getArea (Point* p, int n) {
		double ret = 0;
		for (int i = 1; i < n-1; i++)
			ret += getCross(p[i]-p[0], p[i+1]-p[0]);
		return fabs(ret)/2;
	}
};

namespace Circular {
	using namespace Vectorial;

	/* 直线和原的交点 */
	int getLineCircleIntersection (Point p, Point q, Circle O, double& t1, double& t2, vector<Point>& sol) {
		Vector v = q - p;
		/* 使用前需清空sol */
		//sol.clear();
		double a = v.x, b = p.x - O.o.x, c = v.y, d = p.y - O.o.y;
		double e = a*a+c*c, f = 2*(a*b+c*d), g = b*b+d*d-O.r*O.r;
		double delta = f*f - 4*e*g;
		if (dcmp(delta) < 0) return 0;
		if (dcmp(delta) == 0) {
			t1 = t2 = -f / (2 * e);
			sol.push_back(p + v * t1);
			return 1;
		}

		t1 = (-f - sqrt(delta)) / (2 * e); sol.push_back(p + v * t1);
		t2 = (-f + sqrt(delta)) / (2 * e); sol.push_back(p + v * t2);
		return 2;
	}

	/* 圆和圆的交点 */
	int getCircleCircleIntersection (Circle o1, Circle o2, vector<Point>& sol) {
		double d = getLength(o1.o - o2.o);

		if (dcmp(d) == 0) {
			if (dcmp(o1.r - o2.r) == 0) return -1;
			return 0;
		}

		if (dcmp(o1.r + o2.r - d) < 0) return 0;
		if (dcmp(fabs(o1.r-o2.r) - d) > 0) return 0;

		double a = getAngle(o2.o - o1.o);
		double da = acos((o1.r*o1.r + d*d - o2.r*o2.r) / (2*o1.r*d));

		Point p1 = o1.point(a-da), p2 = o1.point(a+da);

		sol.push_back(p1);
		if (p1 == p2) return 1;
		sol.push_back(p2);
		return 2;
	}

	/* 过定点作圆的切线 */
	int getTangents (Point p, Circle o, Vector* v) {
		Vector u = o.o - p;
		double d = getLength(u);
		if (d < o.r) return 0;
		else if (dcmp(d - o.r) == 0) {
			v[0] = rotate(u, pi / 2);
			return 1;
		} else {
			double ang = asin(o.r / d);
			v[0] = rotate(u, -ang);
			v[1] = rotate(u, ang);
			return 2;
		}
	}

	/* a[i] 和 b[i] 分别是第i条切线在O1和O2上的切点 */
	int getTangents (Circle o1, Circle o2, Point* a, Point* b) {
		int cnt = 0;
		if (o1.r < o2.r) { swap(o1, o2); swap(a, b); }
		double d2 = getLength(o1.o - o2.o); d2 = d2 * d2;
		double rdif = o1.r - o2.r, rsum = o1.r + o2.r;
		if (d2 < rdif * rdif) return 0;
		if (dcmp(d2) == 0 && dcmp(o1.r - o2.r) == 0) return -1;

		double base = getAngle(o2.o - o1.o);
		if (dcmp(d2 - rdif * rdif) == 0) {
			a[cnt] = o1.point(base); b[cnt] = o2.point(base); cnt++;
			return cnt;
		}

		double ang = acos( (o1.r - o2.r) / sqrt(d2) );
		a[cnt] = o1.point(base+ang); b[cnt] = o2.point(base+ang); cnt++;
		a[cnt] = o1.point(base-ang); b[cnt] = o2.point(base-ang); cnt++;

		if (dcmp(d2 - rsum * rsum) == 0) {
			a[cnt] = o1.point(base); b[cnt] = o2.point(base); cnt++;
		} else if (d2 > rsum * rsum) {
			double ang = acos( (o1.r + o2.r) / sqrt(d2) );
			a[cnt] = o1.point(base+ang); b[cnt] = o2.point(base+ang); cnt++;
			a[cnt] = o1.point(base-ang); b[cnt] = o2.point(base-ang); cnt++;
		}
		return cnt;
	}
};

using namespace Vectorial;
using namespace Linear;
using namespace Circular;

Circle CircumscribedCircle(Point p1, Point p2, Point p3) {  
	double Bx = p2.x - p1.x, By = p2.y - p1.y;  
	double Cx = p3.x - p1.x, Cy = p3.y - p1.y;  
	double D = 2 * (Bx * Cy - By * Cx);  
	double cx = (Cy * (Bx * Bx + By * By) - By * (Cx * Cx + Cy * Cy)) / D + p1.x;  
	double cy = (Bx * (Cx * Cx + Cy * Cy) - Cx * (Bx * Bx + By * By)) / D + p1.y;  
	Point p = Point(cx, cy);  
	return Circle(p, getLength(p1 - p));  
}

Circle InscribedCircle(Point p1, Point p2, Point p3) {  
	double a = getLength(p2 - p3);  
	double b = getLength(p3 - p1);  
	double c = getLength(p1 - p2);  
	Point p = (p1 * a + p2 * b + p3 * c) / (a + b + c);  
	return Circle(p, getDistanceToLine(p, p1, p2));  
} 

int TangentLineThroughPoint(Circle o, Point p, double* rad) {
	double tmp;
	Vector v[5];
	vector<Point> sol;
	int n = getTangents(p, o, v);
	for (int i = 0; i < n; i++) {
		rad[i] = getAngle(v[i], Vector(1, 0));
		if (dcmp(v[i].y) <= 0) rad[i] = pi - rad[i];
	}
	return n;
}

void CircleThroughAPointAndTangentToALineWithRadius (Circle O, Point A, Point B) {
	double t1, t2;
	vector<Point> sol;
	Vector v = getNormal(A - B);
	getLineCircleIntersection (A + v * O.r, B + v * O.r, O, t1, t2, sol);
	getLineCircleIntersection (A - v * O.r, B - v * O.r, O, t1, t2, sol);

	sort(sol.begin(), sol.end());
	printf("[");
	for (int i = 0; i < sol.size(); i++) {
		if (i) printf(",");
		printf("(%.6lf,%.6lf)", sol[i].x, sol[i].y);
	}
	printf("]\n");
}

void CircleTangentToTwoLinesWithRadius(Point a, Point b, Point c, Point d, double r) {
	double t1, t2;
	Point o;
	vector<Point> sol;
	Vector v1 = getNormal(a - b), v2 = getNormal(c - d);

	getIntersection (a+v1*r, b-a, c+v2*r, d-c, o);
	sol.push_back(o);
	getIntersection (a+v1*r, b-a, c-v2*r, d-c, o);
	sol.push_back(o);
	getIntersection (a-v1*r, b-a, c+v2*r, d-c, o);
	sol.push_back(o);
	getIntersection (a-v1*r, b-a, c-v2*r, d-c, o);
	sol.push_back(o);

	sort(sol.begin(), sol.end());
	printf("[");
	for (int i = 0; i < sol.size(); i++) {
		if (i) printf(",");
		printf("(%.6lf,%.6lf)", sol[i].x, sol[i].y);
	}
	printf("]\n");
}

int main () {
	double r, t[10];
	Point a, b, c, d;
	char order[105];

	while (scanf("%s", order) == 1) {
		if (strcmp(order, "CircumscribedCircle") == 0) {
			a.read(), b.read(), c.read();
			Circle O = CircumscribedCircle(a, b, c);
			printf("(%.6lf,%.6lf,%.6lf)\n", O.o.x, O.o.y, O.r);
		} else if (strcmp(order, "InscribedCircle") == 0) {
			a.read(), b.read(), c.read();
			Circle O = InscribedCircle(a, b, c);
			printf("(%.6lf,%.6lf,%.6lf)\n", O.o.x, O.o.y, O.r);
		} else if (strcmp(order, "TangentLineThroughPoint") == 0) {
			a.read(), scanf("%lf", &r), b.read();
			int n = TangentLineThroughPoint(Circle(a, r), b, t);

			sort(t, t + n);
			printf("[");
			for (int i = 0; i < n; i++) {
				if (i) printf(",");
				printf("%.6lf", t[i] * 180 / pi);
			}
			printf("]\n");

		} else if (strcmp(order, "CircleThroughAPointAndTangentToALineWithRadius") == 0) {
			a.read(), b.read(), c.read(), scanf("%lf", &r);
			CircleThroughAPointAndTangentToALineWithRadius(Circle(a, r), b, c);

		} else if (strcmp(order, "CircleTangentToTwoLinesWithRadius") == 0) {
			a.read(), b.read(), c.read(), d.read(), scanf("%lf", &r);
			CircleTangentToTwoLinesWithRadius(a, b, c, d, r);
		} else {
			double r1, r2;
			a.read(), scanf("%lf", &r1), b.read(), scanf("%lf%lf", &r2, &r);
			vector<Point> sol;
			getCircleCircleIntersection (Circle(a, r1+r), Circle(b, r2+r), sol);

			sort(sol.begin(), sol.end());
			printf("[");
			for (int i = 0; i < sol.size(); i++) {
				if (i) printf(",");
				printf("(%.6lf,%.6lf)", sol[i].x, sol[i].y);
			}
			printf("]\n");
		}
	}
	return 0;
}

uva 12304 - 2D Geometry 110 in 1!（几何）

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原文地址：http://blog.csdn.net/keshuai19940722/article/details/47731689